Five Ways to See Chemical Reactions

Gas Bubbles

• You can see gas bubbles form when you mix vinegar and baking soda together. The popular elementary school science experiment making red lava flow from a volcano is done mixing these compounds and adding red food coloring.

Color Change

• Many times when two liquid chemicals are mixed together, the resulting solution will change color. This is the most obvious sign of a chemical reaction. But other color changes can be observed only when special chemical detection glasses are worn. Crime scene investigators treat stains and other evidence with a clear reacting chemical. Only when special glasses are put on can the stain be seen. Leaves on trees change color because they lose the chemicals that make them green.

Heating

• Chemical reactions can produce compounds that are warm or hot and even produce flames. This is known as an "exothermic reaction." A simple, safe experiment can be done at home by mixing baking soda, calcium chloride and water. These compounds are room temperature, but when mixed together create heat. A rather violent and dangerous reaction occurs when chlorine is added to sodium. That is why you should never mix chlorine bleach with the drain cleaner sodium hydroxide. It can cause explosions or create flames and dangerous gases.

Chilling

• An endothermic reaction is when something becomes cool or cold to the touch or ice crystals form. This chemical reaction happens inside instant cold packs that typically consist of two compounds -- urea and ammonium chloride -- in separate containers within a plastic bag. When the bag is bent and the inside containers are broken, the two compounds mix together and begin to react. They absorb heat from the surrounding environment and the bag gets cold.

Electricity

• We can witness electricity being produced. Batteries change chemical energy of substances to electrical energy. A zinc casing with a center rod of carbon pushed into the middle of it, surrounded by an electrolyte compound of ground carbon, zinc chloride, ammonia salts and magnesium dioxide, makes our small appliances operate.