Introduction
Source: Glendale Community College, Glendale, CA
Chemistry is a scary subject to many. However, we eat, drink and use chemicals but do not know much about them. In order to understand our environment, we must understand chemistry. In order to take care of our environment or to clean it up, we have to apply chemistry. To help dispel chemophobia, here I will demonstrate some basic concepts of chemistry using commonly available chemicals found in the supermarkets and hardware stores. These demonstrations are designed according to my 9-R principles: Reinforce concepts, Rouse interest, Relevant, Reduce fear, Reaily available, Relatively inexpensive, Reltively safe, Reduced preparation time, Reduced disposal problems. Instructions and explanations are written with non-technical readers in mind, and no chemical formulas and equations are used.
You can do these demonstrations and or experiments yourself at home by following the instructions and safety precautions given. You should also read the American Chemical Society Safety Guidlines. Always wear goggles to protect your eyes, and never eat, drink or taste any of the chemicals and solutions. Some of these demonstrations can be presented in a magic show format. I hope you enjoy them and learn from them. More detailed information and more technical explanations can be found in Chemical Magic from the Grocery Store by Andy Sae (Kendall/Hunt Publishing Company, 1996).
Commercial products used in these demonstrations do not constitute endorsments by the author. Choices are made on the basis of active ingredients, appropriate chemical and physical properties, and the 9 R's mentioned above.
Commercial products used in these demonstrations do not constitute endorsments by the author. Choices are made on the basis of active ingredients, appropriate chemical and physical properties, and the 9 R's mentioned above.
1. Density
All matter (objects, substances) has mass (weight) and occupies space (volume). Therefore, every substance or object has a density defined by its mass divided by volume. Density is a characteristic (property) of every substance and is not affected by how much of that substance you have.
Demo 1 Red, White And Blue, I
(Video Link)
Materials: red food color, light syrup, milk (or coffee creamer), blue kerosene lamp oil, clear plastic cup
Precautions: Wear goggles. Lamp oil is flammable. Do not taste or drink syrup or milk after being used in the demonstration.
Disposal: Decant lamp oil back into the bottle. Dispose milk and syrup down the sink.
Procedure: Dye a bottle of light syrup red with food color. Add the red syrup, milk and blue lamp oil into the cup in any order to create a red, white, and blue density column.
Explanation: Each of the three liquids has its own density. The one that is densest sinks to the bottom, the one in the middle is less dense and the one on top is least dense
Materials: red food color, light syrup, milk (or coffee creamer), blue kerosene lamp oil, clear plastic cupPrecautions: Wear goggles. Lamp oil is flammable. Do not taste or drink syrup or milk after being used in the demonstration.
Disposal: Decant lamp oil back into the bottle. Dispose milk and syrup down the sink.
Procedure: Dye a bottle of light syrup red with food color. Add the red syrup, milk and blue lamp oil into the cup in any order to create a red, white, and blue density column.
Explanation: Each of the three liquids has its own density. The one that is densest sinks to the bottom, the one in the middle is less dense and the one on top is least dense
Demo 2 Sink Or Swim
Materials: 12-oz can of regular soda, 12-oz can of diet soda, large glass bowl, water
Precautions: Do not break glass bowl.
Procedure: Put into a large bowl of water, a can of regular soda, and then a can of diet soda of the same kind and brand. The regular soda sinks to the bottom and the diet one floats on top. What will happen if you put a six-pack of the diet soda into the water? Will it sink or will it float?
Explanation: Each can of soda has its own d
ensity and so does the water. The regular soda has sugar in it and therefore weighs more than the diet soda of the same volume. The density of the regular soda is higher than that of the water, therefore, the can of regular soda sinks to the bottom. The diet soda has no sugar but a very small amount of a sugar susbtitute, giving it a lighter weight and thus a lower density than water. (The space above the liquid inside the can contributes to a lower density equally for both cans.) Since the density does not change with the amount of substance, a six-pack diet soda has six times the weight and six times the volume, and therefore, the same density. The whole six-pack will float.
Precautions: Do not break glass bowl.
Procedure: Put into a large bowl of water, a can of regular soda, and then a can of diet soda of the same kind and brand. The regular soda sinks to the bottom and the diet one floats on top. What will happen if you put a six-pack of the diet soda into the water? Will it sink or will it float?
Explanation: Each can of soda has its own d
ensity and so does the water. The regular soda has sugar in it and therefore weighs more than the diet soda of the same volume. The density of the regular soda is higher than that of the water, therefore, the can of regular soda sinks to the bottom. The diet soda has no sugar but a very small amount of a sugar susbtitute, giving it a lighter weight and thus a lower density than water. (The space above the liquid inside the can contributes to a lower density equally for both cans.) Since the density does not change with the amount of substance, a six-pack diet soda has six times the weight and six times the volume, and therefore, the same density. The whole six-pack will float. 2. Solubility
When you put sugar in a glass of water, grains of sugar disappear and the water tastes sweet. What happens is that the sugar molecules move in among the water molecules and soon distribute themselves evenly throughout. We call this a homogeneous mixture of sugar and water or a sugar-water solution. Sugar dissolves in water. If we do the same with alcohol and water, alcohol and water are said to be miscible (for two liquids dissolving in each other). What happens when we mix oil and water?
Demo 3 Oil and Water Don’t Mix
Materials: 10-20 Magnetic marbles (toy store), 10-20 glass marbles, 9” glass pie dish, overhead projector
Precautions: Don’t swallow or lose your marbles.
Disposal: None
Procedure: Mix the magnetic marbles and glass marbles in the pie dish. Rub them slowly with the palm of your hand in a whirling motion. The magnetic marbles will cling together. Pressing on the magnetic marbles, tilt the pie dish up and the glass marbles will separate from the magnetic marbles. The process can be projected on the wall or screen if a clear glass pie dish is used.
Explanation: Glass marbles are analogous to oil molecules that do not have poles (nonpolar) and are not attracted to each other. Magnetic marbles have north and south poles (polar) and are attracted to each other; they are analogous to polar water molecules. When oil and water are mixed, the attraction of the water molecules among themselves excludes the oil molecules, and they separate into two layers. Oil is usually less dense than water and stays on top.
Precautions: Don’t swallow or lose your marbles.
Disposal: None
Procedure: Mix the magnetic marbles and glass marbles in the pie dish. Rub them slowly with the palm of your hand in a whirling motion. The magnetic marbles will cling together. Pressing on the magnetic marbles, tilt the pie dish up and the glass marbles will separate from the magnetic marbles. The process can be projected on the wall or screen if a clear glass pie dish is used.
Explanation: Glass marbles are analogous to oil molecules that do not have poles (nonpolar) and are not attracted to each other. Magnetic marbles have north and south poles (polar) and are attracted to each other; they are analogous to polar water molecules. When oil and water are mixed, the attraction of the water molecules among themselves excludes the oil molecules, and they separate into two layers. Oil is usually less dense than water and stays on top.
Demo 4 Ocean Blue
Materials: Clear plastic bottle with cap, blue food color, mineral oil (baby oil), water
Precautions: None.
Disposal: Pour the mineral oil back into its original bottle. Pour water down the drain.
Procedure: Fill the bottle half full with water. Dye the water blue with food color. Fill the rest of the bottle with mineral oil. Put the cap on tightly so it will not leak. Rock the bottle to simulate ocean waves.
Explanation: Oil and water don’t mix, because oil molecules are nonpolar and water molecules are polar. There is a saying in chemistry, “like dissolves like”. Oil and water are unlike each other and therefore do not dissolve in each other (immiscible). Mineral oil is a hydrocarbon, like gasoline. They are nonpolar molecules. For further insight into polar and nonpolar interaction do Demo 4.
3. Macromolecules
A fundamentally important concept in chemistry and in the understanding our material world is the submicroscopic view of matter. The most useful submicroscopic view of what things are made of is that of the atom1. Only 89 kinds of atoms can be found naturally on this planet. However, they combine to form literally numerous kinds of substances around us. Atoms bond together to form molecules. Molecules are the smallest representative units of a pure substance that is made of two or more atoms. Molecules are too small to be seen by ordinary microscopes even though their relative sizes can vary from two atoms to billions of atoms. The really large ones are often called macromolecules, such as starch, proteins, cellulose, DNA, and many synthetic polymers (commonly called plastics).
Demo 5 A Giant Molecule
Materials: GE Silicone II® sealant, a piece of aluminum foil roughly 2” square
Precautions: Wear goggles. Do not touch your eyes after touching the sealant. Wash your hands after touching. Read the warning label printed on the tube.
Disposal: After the curing process, the sealant may be put in with the trash.
Procedure: Squeeze onto a piece of aluminum foil about an inch of silicone sealant. Let it cure in the air. Touch its surface every now and then to see how it feels. After 24 hours. Take the piece of sealant off the wax paper. Pull on it until it breaks into two parts.
Demo 6 Instant Meringue
Materials: Raw egg, baking soda, citric acid, water, clear plastic cup
Precautions: Wear goggles. Although none of the chemicals is toxic, any of them getting in your eyes will be painful and damaging.
Disposal: The mixture and foams can go down the drain. The egg shell can go into the trash.
Procedure: Put two tsp of water into a clear plastic cup. Add one tsp of egg white from a raw egg and one tsp of baking soda. Mix these ingredients by swirling the cup. Sprinkle one tsp of citric acid into the mixture and swirl the mixture. A thick foam will rise. After the foam has stopped rising, turn the whole cup upside down. There should be no liquid coming out. If there is, use less water next time. This foam is a meringue, or to a chemist, a foamed polymer.
Explanation: A meringue is made by whipping air into the egg white so that tiny air bubbles are trapped to form a foam. In this case, carbon dioxide produced by the reaction of baking soda with citric acid is trapped in a network of entangled egg white protein polymers. Chemists called this a foamed polymer, and the carbon dioxide gas, a blowing agent. Some familiar foamed polymer products are polystyrene foam packing "pop corns", polyurethane foam cushions, polyurethane foam insulations, and poly(vinyl chloride) upholstery products.
1 Each element is made up of its own kind of atoms. An atom has two parts, the nucleus and the electrons. The nucleus is made up of protons and neutrons. The electrons are on the outside.
Precautions: Wear goggles. Although none of the chemicals is toxic, any of them getting in your eyes will be painful and damaging.
Disposal: The mixture and foams can go down the drain. The egg shell can go into the trash.
Procedure: Put two tsp of water into a clear plastic cup. Add one tsp of egg white from a raw egg and one tsp of baking soda. Mix these ingredients by swirling the cup. Sprinkle one tsp of citric acid into the mixture and swirl the mixture. A thick foam will rise. After the foam has stopped rising, turn the whole cup upside down. There should be no liquid coming out. If there is, use less water next time. This foam is a meringue, or to a chemist, a foamed polymer.
Explanation: A meringue is made by whipping air into the egg white so that tiny air bubbles are trapped to form a foam. In this case, carbon dioxide produced by the reaction of baking soda with citric acid is trapped in a network of entangled egg white protein polymers. Chemists called this a foamed polymer, and the carbon dioxide gas, a blowing agent. Some familiar foamed polymer products are polystyrene foam packing "pop corns", polyurethane foam cushions, polyurethane foam insulations, and poly(vinyl chloride) upholstery products.
1 Each element is made up of its own kind of atoms. An atom has two parts, the nucleus and the electrons. The nucleus is made up of protons and neutrons. The electrons are on the outside.
4. Energy I - Heat
Chemistry is not just about matter. It is also about energy. We burn matter to obtain heat energy to drive our cars, to heat our homes, and to cook our food. We generate electricity, and even light, from reaction of chemicals. Some chemical reactions generate heat, called “exothermic” and others absorb heat, called “endothermic”.
Demo 7 Genie In the Bottle
Materials: Baquacil® (27% hydrogen peroxide), IOSAT® pill (potassium iodide), opaque glass bottle with stopper, toilet tissue paper. (A much cheaper alternative, copperas or ferrous sulfate, is available in some garden supply stores, can be used instead of potassium idodide.)
Precautions: Wear goggles. Read warning labels on Baquacil and IOSAT. Baquacil is 27% hydrogen peroxide that can cause skin burns. Do not take the IOSAT pills. After the reaction do not touch the bottle until it cools down.
Disposal: Rinse the contents with water down the sink.
Procedure: Pour two tbsp Baquacil into the bottle. Avoid wetting the mouth of the bottle. Pulverize an IOSAT pill and wrap the powder with a small piece of toilet tissue paper. Wedge the package between the stopper and the inside lip of the bottle without spilling the content into the bottle. When you are ready to let the genie out, pull the stopper and let the package of potassium iodide fall into the bottom. In a few seconds "smoke” comes out of the bottle.
Explanation: The potassium iodide speeds up the decomposition of hydrogen peroxide into oxygen and water. This is a very exothermic reaction. The heat generated is great enough to vaporize water. As the water vapor comes out of the bottle it condenses into small droplets to look like smoke.
Precautions: Wear goggles. Read warning labels on Baquacil and IOSAT. Baquacil is 27% hydrogen peroxide that can cause skin burns. Do not take the IOSAT pills. After the reaction do not touch the bottle until it cools down.
Disposal: Rinse the contents with water down the sink.
Procedure: Pour two tbsp Baquacil into the bottle. Avoid wetting the mouth of the bottle. Pulverize an IOSAT pill and wrap the powder with a small piece of toilet tissue paper. Wedge the package between the stopper and the inside lip of the bottle without spilling the content into the bottle. When you are ready to let the genie out, pull the stopper and let the package of potassium iodide fall into the bottom. In a few seconds "smoke” comes out of the bottle.
Explanation: The potassium iodide speeds up the decomposition of hydrogen peroxide into oxygen and water. This is a very exothermic reaction. The heat generated is great enough to vaporize water. As the water vapor comes out of the bottle it condenses into small droplets to look like smoke.
Demo 8 Money To Burn
Materials: Rubbing alcohol (50% isopropyl alcohol), water, matches, metal tongs, dollar bill, clear plastic cup, large glass dish
Precautions: Wear goggles. Rubbing alcohol is toxic and is not for consumption. Do not let burning alcohol drip on flammable surfaces. Put a large glass dish or a large piece of aluminum foil under the burning dollar. (Do not put this solution on your palm and light it as you might have seen magician do this. This flame is still hot enough to cause severe burns!)
Disposal: Pour alcohol-water mixture down the drain.
Procedure: Mix one part water and two parts rubbing alcohol in a cup. Soak a dollar bill in the mixture. Use a pair of metal tongs to take the bill out of alcohol and position it over the large glass dish. Light the dripping bill with a match.
Explanation: Burning of the alcohol is an exothermic reaction. The water molecules in the mixture absorb part of the heat generated and thus the flame is not hot enough to burn the dollar bill.
Demo 9 Instant Cold Pack
Materials: Instant Cold Compress
Precautions: Read "Cautions" on the package.
Disposal: Throw away with trash.
Procedure: Follow the instruction on the package. By squeezing the package you release the water in an inner pouch. The granules of ammonium nitrate inside the bag dissolve in the water. The bag gets cold.
Explanation: The dissolving process means breaking up bonds in crystals and the mixing of molecules and ions1. For some materials this process is exothermic and in others, such as this one, it is endothermic. When you touch it, it feels cold because heat is absorbed into the package from your fingers
Precautions: Read "Cautions" on the package.
Disposal: Throw away with trash.
Procedure: Follow the instruction on the package. By squeezing the package you release the water in an inner pouch. The granules of ammonium nitrate inside the bag dissolve in the water. The bag gets cold.
Explanation: The dissolving process means breaking up bonds in crystals and the mixing of molecules and ions1. For some materials this process is exothermic and in others, such as this one, it is endothermic. When you touch it, it feels cold because heat is absorbed into the package from your fingers
Demo 10 The Ziploc Reaction
Materials: Baking soda, citric acid, gallon-size Ziploc®, small Ziploc® bag, waterPrecautions: Wear goggles. The inflated plastic bag may pop open spilling the contents which are not harmful unless they get into your eyes.
Disposal: Flush materials down the drain.
Procedure: Put two tbsp of baking soda and two tbsp of citric acid into the gallon-size Ziploc bag. Put four tbsp of water into the small Ziploc bag and put it into the large one without spilling the water; do not seal it. Seal the large bag. When you are ready to perform this demonstration, turn the bag so that the water spills out of the small bag into the big one. An effervescent action takes place and the bag starts to inflate. Touch the bottom of the bag to feel the cold mixture.
Explanation: Baking soda is sodium bicarbonate. It reacts with citric acid to form carbon dioxide that causes the effervescence. The carbon dioxide gas inflates the bag. This is an endothermic reaction, as touching the bottom of the bag confirms the fact that it is cold.
1 Ions are atoms or molecules that carry charges. For example, a hydrogen atom loses one electron and becomes a positively charged hydrogen ion, H+. A molecule of citric acid having a negative charge on it is called a citrate ion.
5. Energy II - Electricity
There are three major ways of producing energy – combustion, nuclear fission and electrochemical cells. Electrochemical cells are also called voltaic cells and batteries in which chemical energy is converted into electricity. In these chemical reactions, electrons are passed from one element or compound1 to another. The flow of electrons constitutes the flow of an electric current.
1Compounds are pure substances that are composed of more than one element in a definite proportion. For example, water is made of the element hydrogen and oxygen in a ration of 2 hydrogen to 1 oxygen. That is why water is known to be "H two O" or having a fomrula of H2O.
Demo 11 Money Is Power
Materials: pennies (2), dimes (2), paper towel, salt, water, multimeter with millivolt scale
Precautions: none
Disposal: Throw the salt wet paper towel in the trash and keep the coins.
Procedure: Clean the coins with detergent using a toothbrush. Fold the towel into three or four layers. Cut three squares to about the size of the coins. Wet them and sprinkle some salt over them. Sandwich the wet paper towel between the coins: dime/penny/dime/penny. Set the multimeter to the lowest millivolt range and measure the voltage by touching the probes of the multimeter to the surface of the upper and lower coins.
Explanation: This is a voltaic cell named after Alessandro Volta (1745-1827) who in 1790 invented it by sandwiching salty wet cardboard between alternating pieces of zinc and copper. The zinc metal passes electrons through the salty wet cardboard to the copper metal, and the flow of electrons can be measured by the multimeter. Can you tell which coin passes electrons to which one in the cell you just built?
Demo 12 What a Lemon
Materials: lemons (2), pennies (2), galvanized nails (2), memory capacitor 0.1F 5.5V, buzzer 1.5V DC, wire leads with alligator clips on both ends (3), multimeter with millivolt scale
Precautions: None
Disposal: Throw lemons away with trash.
Procedure: Insert a penny and a galvanized nail into each of two lemons and connect the two lemons in series. Connect the + pole of a memory capacitor to the penny and the ─ pole to the nail. The voltage should range from 1 to 1.5 volts. Let the capacitor charge for at least three hours. Then use the capacitor to run the buzzer. For connections see pictures below.
Explanation: The zinc metal on the surface of the galvanized nail loses electrons. The electrons pass on to the acid (hydrogen ions) in the lemon. The flow of electrons goes from the galvanized nail to the acid, to the copper penny, through the wire, to the capacitor. When enough electrons are stored in the capacitor, you can drive the buzzer with them. Thus, chemical energy is converted into electrical energy, into mechanical energy, into soundenergy. (This demonstration was presented by Ron Perkins and Mark Straus at CHEM ED '89)
Precautions: None
Disposal: Throw lemons away with trash.
Procedure: Insert a penny and a galvanized nail into each of two lemons and connect the two lemons in series. Connect the + pole of a memory capacitor to the penny and the ─ pole to the nail. The voltage should range from 1 to 1.5 volts. Let the capacitor charge for at least three hours. Then use the capacitor to run the buzzer. For connections see pictures below.
Explanation: The zinc metal on the surface of the galvanized nail loses electrons. The electrons pass on to the acid (hydrogen ions) in the lemon. The flow of electrons goes from the galvanized nail to the acid, to the copper penny, through the wire, to the capacitor. When enough electrons are stored in the capacitor, you can drive the buzzer with them. Thus, chemical energy is converted into electrical energy, into mechanical energy, into soundenergy. (This demonstration was presented by Ron Perkins and Mark Straus at CHEM ED '89)
6. Energy III - Light
Light can come from matter. Again, the electrons play the role. As electrons absorb energy, for example, from being heated strongly, they are said to be raised to a higher energy level. That energy eventually will be released returning the electrons to a lower energy state. That released energy can be in the form of light. The color of the light (wavelength) depends on the amount of energy released by those electrons. The following two demonstrations show two different ways light is emitted from matter.
Demo 13 Will the Real Salt Please Stand
Materials: table salt (sodium chloride), salt substitute (potassium chloride), salt shakers (2), 
propane torch, matches
propane torch, matchesPrecautions: Wear goggles. Be careful with the propane torch. Clear any possible fire hazzard in the vincinity, and have a fire extinguisher ready.
Disposal: None
Procedure: Fill one salt shaker with table salt and another with a salt substitute. Light the small propane torch. The flame should be blue. If the flame is yellow, let it burn a little while until it stays blue. Gently shake the salt shakers one at a time under the air intake of the torch. Identify the real salt and the salt substitute by the color of the flame – yellow for table salt (sodium chloride), lilac (may just appear blue) for salt substitute (potassium chloride).
Explanation: 
When the salts are heated, the atoms that make up the salt absorb heat energy. Electrons within these atoms release the excess energy in the form light. Since sodium atoms are different from potassium atoms, their electrons absorb different amounts of energy. When that energy is released, it is in the form of light with specific wavelengths; that means different colors of light are emitted, yellow for sodium and lilac for potassium.
When the salts are heated, the atoms that make up the salt absorb heat energy. Electrons within these atoms release the excess energy in the form light. Since sodium atoms are different from potassium atoms, their electrons absorb different amounts of energy. When that energy is released, it is in the form of light with specific wavelengths; that means different colors of light are emitted, yellow for sodium and lilac for potassium. Demo 14 High Beam Low Beam
Materials: lightsticks, tall clear glasses (2), hot water, ice water
Precautions: Do not break or cut lightsticks apart. Read warning labels on lightsticks
Disposal: Dispose as instructed on the package.
Procedure: Bend lightsticks to activate them. Put one in the glass of hot water and the other in the ice water. Darken the room and observe the differences in the light intensity.
Explanation: There are a number of chemical reactions that can convert chemical energy to light energy. These processes are known as chemiluminescence. When you bend the lightstick, the vial inside breaks and the chemical inside (usually hydrogen peroxide) mixes with the chemicals outside (a phenyl oxalate ester). The resulting product transfers chemical energy to a dye that emits a colored light. Since chemical reactions run faster at a higher temperature, the lightstick in hot water is brighter.
Precautions: Do not break or cut lightsticks apart. Read warning labels on lightsticks
Disposal: Dispose as instructed on the package.
Procedure: Bend lightsticks to activate them. Put one in the glass of hot water and the other in the ice water. Darken the room and observe the differences in the light intensity.
Explanation: There are a number of chemical reactions that can convert chemical energy to light energy. These processes are known as chemiluminescence. When you bend the lightstick, the vial inside breaks and the chemical inside (usually hydrogen peroxide) mixes with the chemicals outside (a phenyl oxalate ester). The resulting product transfers chemical energy to a dye that emits a colored light. Since chemical reactions run faster at a higher temperature, the lightstick in hot water is brighter.
7. Chemical Reactions
Chemistry is the study of change, 化學 in Chinese. Chemical reactions are changes that result in products with different compositions. For example, if you eat a piece of bread, a series of chemical reactions takes place in your body and two of the end products are carbon dioxide and water. There are thousands of chemical reactions happening in your body every moment and thousands of products are made. There are numerous chemical reactions occurring in our environment, and there are numerous chemical reactions being used in industry to produce all the things that we use.
The rest of the demonstrations on this site are examples of several types of reactions typically taught to beginning chemistry students.
Demo 15 Chained Reactions
Materials: baking soda, citric acid, phenolphthalein solution1, Fruit Fresh®, iodine tincture, lye, spray starch, water, clear plastic cups (6)
Precautions: Wear goggles. Lye is strongly caustic; read warning label on the can.
Disposal: Flush all chemicals down the drain.
Procedure: Spray some starch into the first cup; add water to about 3/4 full and add five drops of phenolphthalein solution. Add 1/8 tsp of lye to the second cup, 1/2 tsp of citric acid to the third, two tsp of baking soda to the fourth, five drops of iodine tincture to the fifth, and a 1/2 tsp of Fruit Fresh to the sixth. To start the demonstration, pour the content in the first cup into the second cup. Then pour the liquid from the second cup into the third one, and so on. The following changes are expected:
1. Cup #1 into Cup #2: a red solution forms.2. Cup #2 into Cup #3: the red solution turns colorless.3. Cup #3 into Cup #4: an effervescent reaction occurs.4. Cup #4 into Cup #5: the colorless solution turns deep blue.5. Cup #5 into Cup #6: the blue solution turns colorless again
Explanation: This demonstration emphasizes on observing changes resulted from chemical reactions. Reaction 1 is an acid-base reaction in which the acid-base indicator1 phenolphthalein turns red because of the basic lye in cup #2. Reaction 2 is another acid-base reaction in which the lye is neutralized by excess citric acid. Reaction 3 is the reaction of citric acid, left over from the previous reaction, with baking soda to form carbon dioxide. Reaction 4 involves the formation of the blue complex from the starch carried over from cup #1 and the iodine tincture in cup #5. Reaction 5 uses the glucose and vitamin C in Fruit Fresh to turn the iodine into iodide, and the blue iodine-starch complex2 breaks down into a colorless solution.
1 You will learn more about acid-base indicators later. Phenolphthalein is one of the most commonly used acid-base indicators. It is also a laxative used to be found in Exlax®, but this formulation is no longer available. Sometimes it is available in the toy store as invisible ink. You may also try to get some from the high school or college chemistry stockroom or chemical suppliers. I have an old box of Exlax pills in my supplies. To make a solution of phenolphtalein from Exlax pills, smash a pill and put it into 4 tbsp of rubbing alcohol.
2 A complex is an assembly of ions and molecules that come together and break apart relatively easily, and it is somewhat different from a compound that has definite composition of elements.
8. Acid-Base
Acids and bases are common substances in nature and in consumer products. In chemistry, acids are substances that provide hydrogen ions, with the symbol H+. If a water solution has lots of H+, it is very acidic, and if it has very little, it is basic. In the middle, we call it neutral. Hence the acidity or basicity is determined by the H+ concentration in a solution. Pure water has a pH of 7. This H+ concentration can be expressed mathematically in a scale, called the pH scale. pH 7 is considered neutral; pH lower than 7 is acidic and higher than 7 basic.
One way to tell if a substance is an acid or a base is by its taste. An acid is sour, and a base is bitter. Obviously it is not smart to taste everything you encounter. Luckily there are many compounds that can serve as acid-base indicators. One of those is phenolphthalein used in Demo 15. These indicator compounds change color at various concentrations of H+, and are therefore made used of to determine the pH of the solutions to which they are added. The reason they change color is that their molecular structure is affected by the H+ in such a way that they absorb light at a different wavelength. The following demonstrations will illustrate the colorful behavior of acid-base indicators.
Demo 16 Caught Red Handed
Materials: galaxy-golden paper, washing soda, lukewarm water, glass bowl
Precautions: Wear goggles. Washing soda is very basic; wash your hands thoroughly after performing this demonstration.
Disposal: The paper can go into the trash. The washing soda solution can be flushed down the drain.
Procedure: Stir one tbsp of washing soda into one quart of lukewarm water in a large bowl. Some solids may stay in the bottom of the bowl. Soak your hand in the bowl of washing soda solution. Take your wet hand out and slap your palm on a piece of galaxy-golden paper to make a “bloody” palm print. Wash your hand.
Explanation: The pigment used to make the golden-yellow color of the paper changes in molecular structure after coming in contact with the basic washing soda solution. This change of structure causes it to absorb light at a different wavelength and to make it look red. Turmeric is a spice that gives food an intense golden-yellow color. It too will turn red when a base such as baking soda is mixed with it.
Demo 17 Is Red Cabbage Red
Materials: Lime-Away® (sulfamic acid) (can use other acids such as hydrochloric, sulfuric and citric), white vinegar, water, baking soda, clear household ammonia, lye, red cabbage, clear plastic cups (6), pitcher, pH paper, hot pot
Precautions: Wear goggles. Avoid getting any of the chemicals in your eyes. Read the product labels.
Disposal: All solutions can be flushed down the drain. The pieces of pH paper can be put in the trash.
Procedure: Boil two to three red cabbage leaves in two cups of tap water for five minutes giving a fairly dark purple liquid. (Microwave cooking will also work.) Dilute the cabbage juice with three cups of tap water in a pitcher. (If the color is too dark, the changes are not as vivid.) Set up six clear plastic cups. The first cup contains one tsp Lime-Away, the second cup one tsp vinegar, third cup water (or leave empty), fourth cup 1/4 tsp baking soda, fifth cup one tsp ammonia, sixth cup 1/8 tsp lye. Pour some diluted cabbage juice into each cup to about one third full. Swirl the cups to mix the contents. Different colors appear. If further investigation is desired, calibrate the colors with standard pH paper by dipping pieces of pH paper into each solution and compare the color of the pH paper to the colors on the chart that comes in the box of pH paper.
Precautions: Wear goggles. Avoid getting any of the chemicals in your eyes. Read the product labels.
Disposal: All solutions can be flushed down the drain. The pieces of pH paper can be put in the trash.
Procedure: Boil two to three red cabbage leaves in two cups of tap water for five minutes giving a fairly dark purple liquid. (Microwave cooking will also work.) Dilute the cabbage juice with three cups of tap water in a pitcher. (If the color is too dark, the changes are not as vivid.) Set up six clear plastic cups. The first cup contains one tsp Lime-Away, the second cup one tsp vinegar, third cup water (or leave empty), fourth cup 1/4 tsp baking soda, fifth cup one tsp ammonia, sixth cup 1/8 tsp lye. Pour some diluted cabbage juice into each cup to about one third full. Swirl the cups to mix the contents. Different colors appear. If further investigation is desired, calibrate the colors with standard pH paper by dipping pieces of pH paper into each solution and compare the color of the pH paper to the colors on the chart that comes in the box of pH paper.
Explanation: . The red cabbage (Brassica oleracea) contains pigments known as anthocyanins. Anthocyanins belong to a large group of water-soluble natural pigments responsible for the attractive colors ranging from strawberry red to the blue color of most fruits, flowers, leaves, and some vegetables. Anthocyanins are commercially used as a colorant in acid solutions such as soft drinks. At various H+ concentrations these compounds rearrange their molecular structures giving rise to different colors. You can compare these colors to colors of standard pH paper. Doing so will give you a standardized pH indicator solution that you can use to determine the pH of an acidic or basic solution of interest.
Demo 18 Red Tornado
Materials: Alka-Seltzer®, Zep® (containing hydrochloric acid) (can use any one of the other acids, such as citric acid, sulfamic acid, sulfuric acid.), red cabbage juice (see Demo17 Procedure for preparation), tall clear glass cylinder, spoon.
Precautions: Wear goggles. Avoid getting Zep in the eyes. Read the product labels.
Disposal: Flush solutions down the drain.
Procedure: Put the red cabbage juice into the glass cylinder. Adjust the color of the solution to red by adding a few drops of Zep slowly. When you are ready to perform the demonstration, use the spoon to stir the liquid in a circular motion to create a vortex. Open a foil packet of Alka-Seltzer and drop one tablet into the cylinder of red cabbage juice and watch the effervescent effect.
Explanation: This is an acid-base neutralization reaction. The Alka-Seltzer is more basic than the red cabbage juice and thus neutralizes the acid that makes the red cabbage juice red. Consequently, the anthocyanin pigments in the red cabbage juice change colors. From the colors obtained in Demo 17 can you tell what pH this solution is after the neutralizing action Alka-Seltzer?
Alka-Seltzer is one of the many antacids on the market. The sodium bicarbonate from the tablet neutralizes the hydrochloric acid in the stomach. Other well known antacids are Tums® (calcium carbonate), Rolaids® (aluminum sodium dihydroxycarbonate), and Phillips® milk of magnesia (magnesium hydroxide).
9. Oxidation-Reduction
We live in an atmosphere with 21% oxygen gas. Oxygen is a rather reactive substance. That is why so many things will burn in the presence of oxygen – combustion. A substance reacting with oxygen is an oxidation reaction. Whenever something is oxidized, however, something else must be reduced. Say, a piece of paper burns; the compound in paper, mostly cellulose, is oxidized into carbon dioxide, and oxygen itself is reduced into water. Therefore, we link these two words together and called these reactions oxidation-reduction reactions. Much of our technology depends on the oxidation of fuel – natural gas, gasoline, and coal. Other oxidation involving oxygen can be slower processes, for example, respiration, rusting of iron.
There is another way to look at oxidation without involving oxygen. When atoms or molecules give up electrons, that is oxidation. When atoms or molecules pick up electrons, that is reduction. For example, in Demo 12, zinc on the surface of the galvanized nail is oxidized as its atoms lose electrons to the acid In the lemon. In refining aluminum from its ore, electricity (flow of electrons) is passed into molten aluminum oxide. The aluminum ions pick up electrons and turn into aluminum metal. Aluminum oxide is reduced into aluminum. Sixteen million tons of aluminum is produced in a year in the world.
There is another way to look at oxidation without involving oxygen. When atoms or molecules give up electrons, that is oxidation. When atoms or molecules pick up electrons, that is reduction. For example, in Demo 12, zinc on the surface of the galvanized nail is oxidized as its atoms lose electrons to the acid In the lemon. In refining aluminum from its ore, electricity (flow of electrons) is passed into molten aluminum oxide. The aluminum ions pick up electrons and turn into aluminum metal. Aluminum oxide is reduced into aluminum. Sixteen million tons of aluminum is produced in a year in the world.
Demo 19 Hot Rods
Materials: rubbing alcohol (70%)1 (or denatured alcohol), matches, toy car, half-gallon size high-density polyethylene milk jug (recycle code 2), duct tape
Precautions: Wear goggles. Stand and put hands on the side and not the back of the mouth of the milk jug. Make sure there is no flammable material in the surrounding, in particular behind the mouth of the milk jug.
Disposal: Condensed liquids inside the jug can be flushed down the drain.
Procedure: Tape milk jug to the roof of the toy car by wrapping the tape under the car. Make sure the car with the milk jug on top can roll freely on its four wheels without tipping to the side. Pour about two tsp of rubbing alcohol into the jug and slosh it around before pouring out the excess alcohol. Lay the car on the floor. Make sure there is no flammable material at least three feet behind the mouth of the milk jug. Position yourself to the side of the milk jug and not behind the mouth of the jug; put a lighted match close to the mouth of the jug to ignite alcohol vapors. After the first run, it will become difficult to do it again in the same milk jug because of the lack of air inside. Use a new one or flush it with air.
Explanation: Alcohol, in this case, isopropyl alcohol, reacts with oxygen in the air to form carbon dioxide and water. This combustion process is exothermic and thus causes the carbon dioxide gas and water vapor to expand giving the milk jug-toy car a push. Jets and rockets fly on the same principles.
1 The rubbing alcohol used to be 70% ethyl alcohol, then it became 70% isopropyl alcohol, and now 50% isopropyl alcohol. (91%, 70% and 50% isopropyl alcohols are avaialbe at drug store.) The higher the alcohol content the more energy will be derived from combustion, and the farther the car will go. Denatured alcohol contains 95% ethyl alcohol.
Demo 20 Turn-Coat Nail
Materials: galvanized nail, Roebic® K77 Root Killer (copper sulfate pentahydrate), vinegar, clear plastic cup
Precautions: Wear goggles. Read the product label.
Disposal: Flush the solution down the drain. Wipe copper off the nail and throw the particles in the trash. The nail can be used again.
Procedure: Put one tsp of the root killer crystals into the clear plastic cup. Fill the cup half full with water. Add 1/8 tsp of vinegar. Stir until the root killer crystals have dissolved completely. Put the nail into the mixture and observe the color change immediately. After half an hour take the nail out, put it on a sheet of white paper and examine the surface of the nail carefully. Notice the color and the small pieces of copper that fell off.
Explanation: Copper sulfate dissolves to form a blue solution. The blue color comes from the copper ions that are in solution. As the copper ions come in contact with the zinc atoms on the surface of the galvanized nail, the zinc atoms pass electrons to the copper ions; zinc is oxidized. Gaining electrons the copper ions are reduced to copper atoms. Since copper atoms are insoluble in water, they form a coat on the surface of the nail. The copper looks black instead the familiar copper tone because the finely divided particles absorb the light that strikes them. The vinegar makes the solution slightly acidic to keep the copper ions in solution.
10. Reaction Rate
Chemical reactions can be fast like an explosion or slow like rusting. The rate of a chemical reaction is affected by conditions such as the concentration of the reactants (substances involved in the reaction), size of the particles, temperature, the energy needed to start the reaction. The rate of chemical reactions are critically important in natural processes such as metabolism, and in manufacturing processes of consumer products. Many of these reactions, natural or synthetic, are speeded up by catalysts. The following demonstrations uses three different catalysts.
Demo 21 Three Little Elephants’ Toothpaste
(Video Link) 
Materials: Baquacil® (27% hydrogen peroxide), Salon CareTM (30 volume hydrogen peroxide), hydrogen peroxide 3% U.S.P., IOSAT® pills (potassium iodide) (3), liquid shampoo or detergent, tall clear glass cylinders (3).
Precautions: Wear goggles. Gloves are recommended. Read product warning labels. Be very careful with Baquacil; it can cause skin burns.
Disposal: After foaming has stopped, flush foams and liquids down the drain.
Procedure: Pour two tbsp of each of the hydrogen peroxide solutions into separate glass cylinders. Add three drops of liquid shampoo to each. Pulverize the IOSAT pills and add one to each of the cylinders. Stand back and watch the foam columns grow.
Explanation: As the hydrogen peroxide decomposes, water and oxygen gas are produced. The oxygen causes the shampoo to foam. Everything else being the same, the higher the concentration of hydrogen peroxide the faster the reaction, and therefore the higher the column of foam. Since the decomposition of hydrogen peroxide is exothermic, the heat generated causes the expansion of the oxygen and increases the size of the foam column. Hydrogen peroxide normally decomposes at a very slow rate. The potassium iodide in the IOSAT pill acts as a catalyst that speeds up the reaction. The name of this demonstration, Elephant’s Toothpaste, has been popular among chemical demonstrators for some time. It refers the column of foam oozing out of the tube.
Demo 22 Light Beer
Materials: hydrogen peroxide 3%, dry yeast, wood splint, matches, clear plastic cup
Precautions: Wear goggles. Remove flammable materials from the surroundings.
Disposal: After the foaming has stopped, flush the yeast and the liquid down the drain.
Procedure: Fill the clear plastic cup one-third full with hydrogen peroxide. Sprinkle ½ tsp of dry yeast over the hydrogen peroxide. Swirl the cup to mix the contents. As the foam is rising, light the wood splint and then blow off the flame. Thrust the glowing wood splint into the "head" of the beer-looking contents in the cup, thus the name “Light Beer”.
Explanation: The decomposition of hydrogen peroxide again is speeded up by a catalyst. This time, the catalyst is an enzyme catalase in the yeast cells. The product, oxygen gas, causes the foaming. Since one of the chemical properties of oxygen is to support burning, the glowing wood splint reignites in an oxygen reach surrounding.
Demo 23 Red Hot Penny
(Video Link)
Materials: copper penny (minted in 1982 or earlier), thin steel wire, acetone, propane torch, metal tongs, matches, pencil, clear glassPrecautions: Wear goggles. Be careful with the propane torch. Acetone is flammable; keep it away from the torch while it is lit. Do not drop red hot penny on the table top or flammable material.
Disposal: The small amount of acetone left can be diluted with water and flushed down the drain.
Procedure: Drill a small hole near the edge and through the penny. Thread a steel wire loop through the hole. Pour one tbsp of acetone in the glass. Hold the penny by the wire with a pair of metal tong and heat the penny to red hot in the flame of the propane torch. Then quickly hang the penny through the wire loop on a pencil over the rim of the glass. Turn down the light and observe the continued but sometimes flickering glow of the penny.
Explanation: The vapor of acetone touches the red hot penny and begins to burn. The copper of the penny acts as a catalyst that speeds up the combustion of acetone into carbon dioxide and water. This reaction produces heat fast enough to keep the penny red hot, and the process continues until the acetone vapor is exhausted. The flicking on the surface of the penny is caused by the changing of temperature. As the vapor touches the surface, it cools the penny down a bit and as it burns, it heats the penny up again. The convection of air around the penny may also contribute to this effect.
11. More Demos 24-28
Demo 24 Making Hydrogen
Materials: aluminum foil, lye, water, matches, baby food jar with perforated lid (with four small holes punched through with a nail)
Precautions: Wear goggles. Lye is very caustic; read warning label on the container. Avoid inhaling the fumes that may come out during the reaction.
Disposal: After the reaction has stopped, flush the remaining liquid down the drain. Do not let unreacted aluminum foil go down the drain; put it in the trash after rinsing it with water. Wash the jar until it does not fill slippery.
Procedure: Roll some aluminum foil into four pea-size balls. Put them into a baby food jar with ½ tsp of lye. Add ¼ tsp of water to wet the lye. Loosely cover the jar with a perforated lid. Do not hold the jar in your hand; it will get very hot. Avoid inhaling fumes. Let the gas (hydrogen) come out for about 10 seconds, and then light it with a match. If air gets in, the lid may pop up with considerable force.
Explanation: Aluminum can react with either acid or base to form hydrogen. (Avoid cleaning aluminum utensils with strong acid and strong base cleaners.) Hydrogen is flammable and it burns to form water. It’s flame should be almost colorless, but the flame on top of the lid is yellow because of the sodium ions in the lye (sodium hydroxide) are being heated up. (see Demo 13)
Demo 25 Making Carbon Dioxide
Materials: citric acid, baking soda, small glass bowl, water, empty clear soft-drink plastic bottle, 9” balloon, matches, small candle
Precautions: Wear goggles.
Disposal: Flush citric acid and baking soda down the drain. Throw the balloon in the trash. Save the candle for later use.
Procedure: Put two tbsp of baking soda and two tbsp of water into the plastic bottle. Put one tbsp of citric acid into the balloon. Stretch the mouth of the balloon onto the mouth of the bottle without spilling citric acid into the bottle. Lift the balloon up to drop the citric acid into the bottle and watch the frothing action and the inflation of the balloon. Put the candle in the glass bowl and light it. While the candle is burning, take the balloon off the bottle without tipping the bottle over. The bottle should still be full of gas. Pour the invisible gas slowly into the glass bowl and watch the candle go out.
Explanation: Baking soda is sodium bicarbonate. When carbonates and bicarbonates are mixed with acid, carbon dioxide is produced. Since citric acid is a solid, water is needed to release the hydrogen ions so that they can react with the bicarbonate ions to form carbon dioxide. When a substance is in its gaseous state, molecules are far apart and therefore, occupy a lot more space. The motion of gas molecules stretches the balloon and inflates it. Carbon dioxide is denser than air and does not support burning. When you pour the carbon dioxide out of the bottle into the bowl, it replaces the air in the bowl and snuffs out the candle. Making use of these properties, one type of fire extinguisher uses baking soda and an acid to generate carbon dioxide to put out fires.
Demo 26 Devil’s Punch
Materials: red cabbage juice (see Demo 17), phenolphathalein solution (see Demo 15), lye, dry ice, water, two tall clear glass cylinders
Precautions: Wear goggles. Read warning label on the can of lye. Handle dry ice with gloves or tongs. Do not drink the solutions.
Disposal: All liquids can be poured down the drain. Let the remaining dry ice sublime outdoors.
Procedure: Fill the first glass cylinder with diluted red cabbage juice. Adjust the color to green using just a few grains of lye at a time; if the color turns yellow, the color won’t change back. In the other cylinder, fill it to the same level with water. Add five drops of phenolphathalein solution, mix, and adjust the color the same way until it is pink. Crack the dry ice into chunks of about the size of a wrist watch. Stir the liquid in the cylinders into a vortex. Drop one chunk of dry ice into each of the two cylinders and watch the “punch” change color.
Explanation: Dry ice is solid carbon dioxide At a temperature higher than − 109oF (− 79oC) (freezing point) and atmospheric pressure, it turns from a solid to a gas (sublimes). Since no liquid phase is involved, it is called “dry ice”. When the dry ice is put into the water, carbon dioxide dissolves in water to form carbonic acid. The acid increases the H+ concentration and thus changes the color of the anthocyanins and the phenolphthalein (see Demo 17). When the dry ice hits the water “smoke” appears. It is actually fog and not smoke. The cold carbon dioxide gas causes the water vapor to condense forming fog.
Demo 27 Devil’s Punch Bowl
Materials: dry ice, dish liquid detergent, water, cotton string, small bowl, large punch bowl or bucket with round and smooth rim.
Precautions: Wear goggles. Do not drink the liquid in the punch bowl.
Disposal: All liquids can be poured down the drain. Let remaining dry ice sublime outdoors.
Procedure: Fill the punch bowl about ¼ full with lukewarm water. Prepare a bubble solution by diluting the dish liquid detergent with equal amount of water. Measure out the string to be a little longer than twice the diameter of the bowl. Soak the string in the diluted detergent solution. Add a chunk of dry ice about the size of your fist into the punch bowl. Double up the detergent soaked string and stretch it out, and then slowly drag it across the rim of the bowl to form a “soap bubble” film across the mouth of the entire bowl. Watch the big dome grow.
Explanation: As the dry ice sublimes (see Demo 26), carbon dioxide gas stretches the detergent film to blow a big bubble (see Demo 25).
Demo 28 Levitating Bubbles
Materials: dry ice, bubble solution, large punch bowl
Precautions: Wear goggles. Use gloves to handle dry ice.
Disposal: Let the remaining dry ice sublime outdoors.
Procedure: Put a piece of dry ice about half the size of your fist on the bottom of the bunch bowl. Let it sit for five to ten minutes. Stand a couple of feet away from the punch bowl. Using the bubble solution and the hoop provided, blow bubbles into the punch bowl. The bubbles will levitate inside the punch bowl. To make it more dramatic, place something in front of the bowl so that the audience will not see the piece of dry ice in the bowl.
Explanation: Carbon dioxide is one and a half times denser than air. As the dry ice sublimes into carbon dioxide gas, it displaces the air in the punch bowl upwards. When the bubbles fall into the punch bowl, they float in a sea of carbon dioxide gas instead of air. The carbon dioxide is dense enough to support the soap bubble film and the air inside.
12. More Demos 29-32
Demo 29 Iceberg
Materials: Denatured alcohol (not rubbing alcohol), ice cube, water, clear glasses or plastic cups (2)
Precautions: Wear goggles. Denatured alcohol is poisonous to drink. It is flammable. Read product label.
Disposal: Take the ice cube out and the denatured alcohol can be saved and used a few more times. It can be flushed down the drain. 
Procedure: Fill the one glass with denatured alcohol and the other glass with water. Add an ice cube to the glass with water first. The ice floats on of the water as an iceberg does in the ocean. Then add another ice cube to the denatured alcohol and watch it sink to the bottom.
Explanation: The density of ice is lower than the density of water and therefore floats on water. The density of ice is higher than that of denatured alcohol and therefore sinks in it. (Water at 0oC = 1.000 g/cm3, ice at 0oC = 0.917 g/cm3, denatured alcohol at 0oC = 0.810 g/cm3)
Demo 30 Ice, Water, And Fire
Materials: Coleman® camp appliance liquid fuel. ice cube, water, matches, wine glass Precautions: Wear goggles. Read product label. Be careful not to knock over the glass with burning fuel. Have a fire extinguisher near by.
Disposal: Let the liquid fuel burn out before disposing the water down the drain.
Procedure: Put one tsp of liquid fuel into the wine glass. Fill the glass nearly to the rim with water. Add an ice cube. Then put a lighted match to the surface of the liquid in the glass, and watch the mixture catch fire.
Explanation: This demonstration applies the principles of solubility and density. The liquid fuel is a non-polar hydrocarbon and therefore does not mix with water and ice. The ice and liquid fuel both have lower density than water and therefore float on top. When a lighted match is brought to the top of the liquid, the hydrocarbon vapor ignites. This is why pouring water over burning oil is a bad idea.
Demo 31 Ice Fishing
Materials: salt, ice cube, water, cotton string 6 inches long, pencil, dish
Precautions: Be careful not to break the dish.
Disposal: salt and ice cube can go down the drain
Procedure: Put the ice cube in the dish. Tie one end of the string to one end of the pencil. Wet the other end of the string and place it on the surface of the ice cube. Sprinkle some salt over the ice cube surface where the string is in contact. Wait 15 to 20 seconds and lift the pencil up like a fishing rod; the ice cube is the fish.
Explanation: Dissolving salt and other substances, such as alcohol and antifreeze, will make water freeze at a temperature lower than the normal freezing temperature of 32o F (0oC). As the salt dissolves on the surface of the ice, the ice melts to form a thin film of water. When the ice cub melts it takes heat away from the immediate surrounding causing the thin film of ice water on the surface of the ice cube and on the string to freeze at a lower temperature and that causing the string to stick to the ice cube. Salt is added to ice in churning homemade ice cream in order to get a temperature lower than 32o F to freeze the ice cream mix.
Demo 32 Cartesian Diver
Materials: clear soft plastic bottle such as a 2-liter soft drink bottle with cap, medicine dropper, water
Precautions: None.
Disposal: Pour water down the drain.
Procedure: Fill the plastic bottle to the top with water. Suck some water into the medicine dropper to about half full. Drop the medicine dropper into the bottle of water, and cap it tightly. Now squeeze the bottle and watch the dropper dive down to the bottom. Release your squeeze and watch the diver come up. If it does not work very well, squeeze it harder. If that still does not work try adjusting the amount of water inside the medicine dropper.
Explanation: The volume of a gas decreases under pressure. The air inside the medicine dropper is compressed by the water pushed into the medicine dropper as you squeeze the bottle. More water in the dropper makes it heavier and therefore, it sinks. As you release the pressure, the air expands and forces the water out of the dropper making it lighter, and it rises.
13. More Demos 33-36
Demo 33 Invisible Ink
Materials: phenolphthalein dolution (see preparation and comments in Demo 15), Windex® spray with ammonia, white paper towel, artist’s paint brush
Precautions: Wear goggles.
Disposal: Throw paper towel in the trash.
Procedure: Use the phenolphthalein solution to paint something on a sheet of paper towel. Let it dry, and then spray it with Windex. Your painting will appear in pink.
Explanation: Since the Windex containing ammonia is basic, it changes the acid-base indicator phenolphthalein from colorless to pink. There is a Windex spray that contains vinegar. That will not work, since it is acidic and it will cause the phenolphthalein to stay colorless.
Demo 34 Turning Water Into Kool-Aid
Materials: phenolphthalein solution (see preparation and comments in Demo 15), citric acid, lye, water, clear plastic cup, drinking straw, white paper towel
Precautions: Wear goggles. Read product label on the can of lye. Do not drink the solution in the cup.
Disposal: Flush liquid down the drain. Throw the straw in the trash.
Procedure: Fill the plastic cup ¾ full with water. Add five drops of phenolphthalein solution. Use small pieces of paper towel to plug both ends of the drinking draw. Stuff the paper into the straw so that it will not fall out easily. Wet both ends with water. Stuff some solid citric acid into one end, and lye into the other end. They should stick to the wet paper plugs inside the straw. Wipe off the citric acid and lye that stick to the ouside of the straw. Begin the demonstration by stirring the water in the cup with the end of the straw containing lye. The solution turns pink. Turn the straw around and stir the solution in the cup with the other end of the straw containing citric acid. The citric acid should neutralize the lye and change the indicator back to colorless. If this does not work, adjust the amounts of lye and citric acid used.
Explanation: The lye is basic and it turns the phenolphthalein indicator to pink. The citric acid neutralizes the lye, and an excess of citric acid causes the solution to become acidic. In turn, the phenolphthalein indicator changes to colorless. (A variation to this demo would be to use a diluted cranberry cocktail instead of the phenolphthalein-water mixture. What color changes do you expect?)
Demo 35 Cool Breath
Materials: phenolphthalein solution (see preparation and comments in Demo 15), lye, water, clear plastic cup, drinking straw
Precautions: Wear goggles. Read product label on the can of lye. Do not drink the solution in the cup.
Disposal: Pour the solution down the drain.
Procedure: Fill the plastic cup ¾ full with water. Add five drops of phenolphthalein solution. Add a few grains of lye to turn the solution pink. Begin the demonstration by putting the drinking straw into the solution in the cup and blow gently into the solution through the straw. Continue blowing and watch the color of the solution slowly change from pink to colorless.
Explanation: The lye makes the solution basic and turns the phenolphthalein indicator pink. As you blow into the solution, carbon dioxide from your breath dissolves in the water to form carbonic acid. When you blow long enough, the lye is neutralized by the carbonic acid and the phenolphthalein turns colorless. Do not use too much lye; otherwise, you will be out of breath before the solution changes color.
Demo 36 Red, White, And Blue, II
Materials: phenolphthalein (see preparation and comments in Demo 15), Epsom salt, Roebic® K-77 root killer, clear household ammonia, water, clear plastic cups (3)
Precautions: Wear goggles. Read labels on all products.
Disposal: All solutions can be disposed of down the drain.
Procedure: Put 5 drops of phenolphthalein solution into the first cup and two tsp of Epsom salt and just enough water to dissolve the salt in the second cup. Crush 1/8 tsp of copper sulfate crystals and add them to the third cup. Start the demonstration by pouring clear household ammonia solution directly from the bottle into the first cup, then the second, and the third cup. Red (hot pink), white and blue solutions appear in the cups respectively.
Explanation: Ammonia solution is basic. It turns the phenolphthalein solution in the first cup red or hot pink. In the second cup, a white solid, magnesium hydroxide, is formed when the magnesium ions in the Epsom salt (magnesium sulfate heptahydrate) reacts with basic ammonia. In the third cup, the ammonia reacts with the copper ions in the root killer (copper sulfate pentahydrate) to form an intense blue ammonia-copper ion complex.
14. More Demos 37-41
Demo 37 Smoke Signal
Materials: bowl cleaner with 23% hydrochloric acid, clear household ammonia, clear plastic cups (2), paper or plastic sheet
Precautions: Wear goggles. Read product warning labels. Do not inhale fumes. The hydrochloric acid and ammonia vapors are toxic. However, toxicity is dose dependent. Just inhaling enough to be able to smell the two substances is not toxic enough to be harmful. If hydrochloric acid is spilled, pour some baking soda over it and clean it up with water. Wear gloves.
Disposal: Due to the small amounts used, they can be flushed down the drain.
Procedure: Put ¼ tsp of the bowl cleaner liquid in a clear plastic cup and cover it with the a piece of paper or plastic. Put one tsp of household ammonia into the other plastic cup. Take off the cover of the cup that contains the bowl cleaner, and hold the cup with ammonia over it. A white smoke will form.
Explanation: When the vapor of hydrochloric acid comes in contact with the vapor of ammonia, their molecules collide, and a new product is formed. This product is ammonium chloride which is a white solid. A finely divided solid suspended in air is a smoke. Ammonium chloride is nontoxic.
Demo 38 Inflated Penny
Materials: penny (1983 or newer), pH MinusTM (10% sulfuric acid), baking soda, clear plastic cup
Precautions: Wear goggles. Read product warning label.
Disposal: Do this in the sink. Add a tbsp of baking soda to the unreacted acid and then flush the mixture down the drain. The copper shell of the penny can be put in the trash.
Procedure: Fill the clear plastic cup one third full with pH Minus solution. Using a file, score the edges of both sides of a penny at three or four places to expose the silvery metal inside the penny. Put the penny into the cup of pH Minus. Streams of small bubbles should appear. If there is no bubble coming out, you need to score the penny a little deeper. Just let it sit in a safe place. This can take hours. If bubbles stop coming out, pour the solution out into the sink and add more acid. When the inside metal is all dissolved, the penny copper shell will float to the top.
Explanation: Starting in 1983, instead of the solid copper, American pennies are made of zinc coated with a think layer of copper . The zinc metal inside reacts with dilute sulfuric acid to form zinc sulfate and hydrogen (bubbles). Copper does not react with dilute acids. After the zinc is dissolved (reacted), only the copper shell of the penny is left. Even though copper has a higher density than water, the copper shell floats, because some gas bubbles are trapped inside the shell.
Demo 39 My Cup Of Tea
Materials: Copperas (ferrous sulfate purchased in gardening supply stores but is getting hard to find) or pulverized iron supplement pill (does not work as well), hydrogen peroxide (3%), tea (instant or brewed), clear plastic cup (2), tea pot.
Precautions: Wear goggles. Do not drink the tea.
Disposal: Flush tea and iron compound down the drain.
Procedure: Put 1/8 tsp of copperas into one plastic cup. Add a few drops of hydrogen peroxide on top of the copperas. To start the demonstration, pour some tea into the empty cup to show the regular tea color. Then, pour some tea into the cup containing copperas. The tea immediately turns black.
Explanation: The hydrogen peroxide oxidizes the ferrous ion (less oxidized form of iron) into ferric ion (more oxidized form of iron). When ferric ions come in contact with tannin, found in tea, coffee and many plant materials, a black color complex (see footnote 2, Demo 15) forms. This black complex has been used as a black ink.
Demo 40 Clear Out Of the Blue
Materials: spray starch, iodine tincture, Fruit Fresh®, water, clear plastic cups (3)
Precautions: Wear goggles. Read product labels.
Disposal: All liquids can be flushed down the drain.
Procedure: Fill the first cup ¾ full with water. Spray some starch into the water and stir the mixture. Wait for the small bubbles to disappear before starting the demonstration. In the second cup add ten drops of iodine tincture. In the third cup add ¼ tsp of Fruit Fresh powder. Begin the demonstration by pouring the clear solution in the first cup into the second cup containing iodine tincture. The solution turns into a deep blue color; it may appear black. Then pour this blue solution into the third cup containing the Fruit Fresh powder. The dark blue solution turns back to colorless.
Explanation: Iodine tincture is a mixture of iodine and iodide in an alcoholic solution. The iodine-iodide complex ion combines with starch molecules to form another complex that has an intense blue color. When this blue complex is mixed with the Fruit Fresh powder, the glucose and the vitamin C (L-ascorbic acid) in the Fruit Fresh pass electrons to the iodine and turn it into iodide. The reduction of iodine to iodinde destroys the iodine-iodide complex and therefore the deep blue complex disappears.
Demo 41 Ice Is Blue
Materials: spray starch, iodine tincture, water, ice “cube” (a fairly large chunk) tall clear glass
Precautions: Wear goggles. Be careful with hot liquid.
Disposal: Pour the solutions down the drain.
Procedure: Spray some starch into the glass of water. Add ten drops of iodine tincture and stir it. The solution will turn blue. Put the glass of blue solution into the microwave and heat the solution to near boiling. The blue color will disappear. Take it out and let it cool back down close to room temperature. Put a large ice cube into the glass. Watch streams of blue coming off the melting ice cube.
Explanation: In Demo 40 and Demo 15, you have observed the intense blue complex formed by iodine-iodide and starch. In this demonstration, however, the blue color disappears after the liquid is heated up in the microwave. This is probably due to the deformation of the starch macromolecules and thus prevents them from combining with the iodine-iodide to form the blue complex. As the ice melts, streams of cool water allows the starch molecules to reform, and to make the blue complex again.
15. More Demo 42 - 46
The following demonstrations show some of the varied properties of polymers. Natural and synthetic polymers have specific properties that are a result of their molecular designs. These properties are usually not found in small molecules. Making use of these properties chemists have made numerous useful, and sometimes not so useful, consumer products.
Demo 42 Silme
Materials: Elmer’s Glue-All®, borax, food color, water, clear plastic cups (2), stirrer or spoon
Precautions: Wear goggles. After touching or playing with the polymer, wash your hands.
Disposal: Throw the “slime” and stirrer into the trash. Pour left over borax down the drain.
Procedure: Pour two tbsp of Elmer’s Glue-All in to a clear plastic cup and a drop of food color; stir to mix the color evenly. Dissolve two tsp of borax in two tbsp water. Or, simply make a saturated borax solution (some left undissolved on the bottom). Pour one tsp of the borax solution into the Elmer’s Glue-All and quickly stir the mixture. Pull the slime up with the stirrer. Touch the slime to feel its texture. It is no long a sticky glue.
Explanation: Elmer’s Glue-All itself is made of the polymer polyvinyl acetate. The borax reacts with these polymers through a process called cross-linking. Cross-linking ties up the polyvinyl acetate macromolecules to form a massive network making the viscous but fluid glue into a solid mass. This a similar process as in Demo 5.
Demo 43 Thumb Mightier Than Hammer
Materials: Silly Putty® or similar silicone polymer toy putty, hammer
Precautions: Do not hit your thumb with the hammer.
Disposal: Put the putty back into its shell.
Procedure: Roll the putty up into a ball. On a solid surface hit the putty with a quick, sharp blow. The putty ball bounces but does not flatten. Then press the putty ball with your thumb. It flattens out easily!
Explanation: This kind of polymer has a viscoelastic propert; it flows and stretches very slowly. A sharp blow from the hammer does not give the polymers enough time to move away from each other and the elastic property causes the polymers to bounce back. However, when you press the ball of polymers with your thumb, the polymers ooze out, and the ball flattens.
Demo 44 Hidden Image
Materials: Soil Moist® or other brands of polyacrylamide gel “crystals”, water, glass with a clear bottom, picture
Precautions: Do not let children eat the gel.
Disposal: Do not flush the material down the drain or toilet; drain the water and put the gel pieces in the trash.
Procedure: Add 1/4 tsp Soil Moist to a cup of water and let it swell fully. It may take half a day or longer. Add more water if necessary. Cut a picture to the size of the bottom of the glass. Put the glass over the cut out picture. Drain the water from the swollen Soil Moist; put pieces of the gel into the glass to cover the bottom. The gel pieces block the view of the pictures. Start the demo by slowly pouring water into the glass until the gel pieces are completely covered. The picture underneath the glass will appear as the gel pieces seem to disappear.
Explanation: Before the water is added to the glass, the light is deflected by the gel pieces making it impossible to see through; the view of the picture underneath is blocked. The polyacrylamide absorbs so much water that its refractive index is almost the same as water. When the water is poured into the glass and fills the space between the gel pieces, light is no longer bent and therefore goes straight through revealing the writing underneath.
Demo 45 Invincible Bag
Materials: sandwich-size Ziploc® bag, sharpened pencil, pie pan
Precautions: Wear goggles.
Disposal: Dispose bag in the trash.
Procedure: Fill the Ziploc bag half full with water and zip it up. Hold it over the sink or a pie pan - just in case it bursts. Quickly thrust the sharp pencil in one side of the bag and out the other . The water should not leak out.
Explanation: Elasticity is an important property of a number of natural and synthetic polymers. The pencil pokes a hole in the polymer network that makes up the bag, the polymers stretch out to let the pencil through. Then they reseal the hole around the pencil to prevent the bag from leaking.
Demo 46 The Bottomless Mug
Materials: acetone, polystyrene packing “peanuts,” quart-size glass bowl, coffee mug (non-plastic)
Precautions: Wear goggles. Acetone is flammable!
Disposal: Let acetone evaporate into the air outdoors. Put the dried polystyrene at the bottom of the mug in the trash or in the recycle bin that accepts #6 plastics.
Procedure: Pour two tbsp of acetone into the coffee mug. Fill the glass bowl with polystyrene packing peanuts. Start picking up the peanuts and dropping them into the coffee mug. You can easily put all the peanuts into the coffee mug.
Explanation: The packing peanuts are made from a small amount of polystyrene puffed up by a blowing agent. (See Demo 6) This is an expanded polystyrene foamed polymer, or commonly known as “Styrofoam.” When Styrofoam objects are put into acetone, they do not dissolve; the polymers soften or relax, causing the foam structure to collapse, leaving a small, compact pile of polystyrene.
The End
(For Now)
Murry Shohat
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Congratulations, Silver Badge
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Great work, keep it up,
Murry Shohat and Peter Baskerville
Rajamanickam Antonimuthu
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Very Useful article for School Students/Teachers
Learning with experiments will encourage the students to learn/understand science
I am very much impressed by this knol. This knol shows the author's dedication, sincerity hard work ,and interest towards his subject. Each and every demo is very clearly explained with related pictures.
Coming to the presentation neatly aligned with proper headings.
I hope his students will be enjoying his session.
Excellent work!!!
Thanks,
Rajamanickam
Anonymous
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demonstration 1(Density)
Siroun Pakdaman(Chem 110 lab)
Peter Baskerville
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It's brilliant Andy
Here are some of my suggestions:
You may need to think about splitting up this Knol. Once you get past 10 <H2> headers you lose the table of contents description (apart from the 'more' tag). Can these demos be type-grouped into 10's and create separate Knols? These Knols can still be grouped together in a KnolBook see mine ...
http://knol.google.c
Don't be afraid about making the photo's bigger. This is a very visual Knol and topic. Also turn Wrap ON. This will embed the photos into the text and make the reader experience more cohesive.
The new-section line that you use at the end could be used to separate each Demo. This again would add to the look and presentation of this outstanding Knol.
The video links are great, but how about making a few visual on the Knol using the insert a video selection on the menu.
Overall, an outstanding Knol and a good example of how a Knol can be used to foster learning to a knowledge hungry people. I encourage you to reinvest some more time here to turn an outstanding Knol into a example for all. 10 stars!
Andy
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Krishan Maggon
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Great Article 5*
I enjoyed your excellent article with video links and ease of reading. It is great for students and children to have fun in learning chemistry. When is your next article. Please keep on posting.
I have provided a link to your knol as a model or as a super knol?
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Journal of Therapeutic Biotechnology (JTB)
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Andy
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