Non-Popping Balloon

When water is placed in a balloon, the balloon can be placed over a flame without popping. Water absorbs the heat from the flame, so the rubber of the balloon does not become weak and break like it does with the dry balloon.

Red Cabbage Indicator

red cabbage indicator in common household solutions

Anthocyanin, which is found in red cabbage, is a natural indicator that can be easily extracted.

Pepper in Water

Water has a very high surface tension because of the strong hydrogen bonding between water molecules, which allows the pepper to float on top of the water. When a small amount of soap is added it forms a monolayer on the surface. The monolayer spreads away from the point of contact causing the pepper to move to the edges of the dish.

Non-Burning Dollar Bill

non burning dollar bill ethanol and water

When the bill is dipped in the water/alcohol mixture then lit on fire, the water protects the bill from burning. A large amount of the alcohol is vaporized from the heat causing a large flame around the bill.
C2H5OH + 3O2 → 2CO2 + 3H2O

Make Water A Gel

sodium polyacrylate forms a gel with water

This demo uses sodium polyacrylate, a super absorbing polymer found in diapers, to turn water into a gel. The sodium polyacrylate has carboxylate anion portions and sodium cation portions. Water is attracted to the sodium ions, thus it enters the polymer through osmosis and the polymer swells and the sodium carboxylate is ionized. The anionic carboxylates on the polymer repel each other, causing the polymer to swell, trap the water, and form a gel. When NaCl is added the increase of electrolytes (ions) in the water shield the repulsion of the carboxylates, thus contracting the polymer and expelling the liquid water.

M&M Color Wheel

M&Ms in water, candy coating dissolving

When M&M’s are placed in water, the outer shell, which is made of sugar, dissolves. The sugar moves from a place of high concentration (the M&M) to a place of low concentration (the water away from the M&M). When the sugar shell dissolves and moves outward, it takes the layer of food dye with it. When more than one M&M is placed into a petri dish the colors do not mix because the concentration of sugar at the interface is approximately the same. Also, around the bottom of the M&M water appears cloudy because the sugar that is dissolved is more dense than the water, so it sinks.

Lemon Fizz

lemon reaction with baking soda

When basic baking soda (NaHCO3) is combined with acidic lemon juice (mainly citric acid, H3C6H5O7) an acid base reaction occurs. The reaction releases CO2 which can be captured using dish soap to form bubbles.
H3C6H5O7 (aq) + 3 NaHCO3 (s) → 3 CO2 (g) + 3 H2O (l) + Na3C6H5O7 (aq)

Dry Ice in Universal Indicator

dry ice universal indicator acid base reaction

Universal indicator goes from red (pH 4) to violet (pH10) as the pH of a substance changes. Adding NaOH to water starts the solution off at pH 8-9 (blue). When dry ice is added to water it forms carbonic acid, and lowers the pH, which is the reason for the color changes. The “fog” that we see is condensed water vapor though, not carbon dioxide gas.

Disappearing Ink

This demo uses acid base chemistry and an indicator to make an ink that will appear or disappear depending on the solution added to it. Phenolphthalein, which is clear, reacts with a base, and then turns pink.

Chemistry Pop Guns

This demo harnesses the reaction of baking soda and vinegar to blow a cork off a test tube.
NaHCO3 (s) + CH3COOH (aq) →CO2 (g) + H2O (l) + CH3COONa (aq)

Bending Water

bending water with a balloon, charging by induction

When the balloon is rubbed on a pair of jeans, electrons are wiped from the jeans to the balloon, causing a net negative charge on the balloon. The charged balloon is held near a thin stream of water. Charges in the water rearrange so that the positive charges in the water become attracted to the negatively charged balloon, and the stream of water bends. The rearranging of charges is pronounced because water is a polar molecule.

Ammonium Nitrate in Water

ammonium nitrate ions in solution

When ammonium nitrate is dissolved in water it feels cold, which indicates an endothermic reaction.
NH4NO3 (s) → NH4+ (aq) + NO3- (aq)