Chemical reactions occur every day all around us. A chemical reaction is a process where one type of substance is chemically converted to another substance. That fizzling toilet bowl cleaner is a chemical reaction. The fire in your fireplace is another type of chemical reaction. The smoke that comes out of Dad's ears when you lose one of his favorite golf clubs is a result of a chemical reaction. OK, so maybe that's a bad example. This experiment demonstrates a chemical reaction that's fairly common all around us (and we don't have to touch Dad's golf clubs to make this one work).
- Put the thermometer in the jar and close the lid.
- Wait about 5 minutes and write down the temperature.
- Remove the thermometer from the jar.
- Soak a piece of steel wool in vinegar for one minute.
- Squeeze the vinegar out of the steel wool pad. Wrap the steel wool around the bulb of the thermometer.
- Place the thermometer and steel wool back into the jar and close the lid.
- Wait 5 minutes.
- Now take a look at the temperature.
What happened to the temperature? Are you surprised that it the temperature rose (sorry this experiment didn't produce any smoke but then again, you didn't get grounded either).
The vinegar removes any protective coating from the steel wool, allowing the iron in the steel to rust. Rusting is a slow combination of iron with oxygen. When this happens, heat energy is released. The heat released by the rusting of the iron causes the mercury in the thermometer to expand and rise.
Parent/Teacher/Advanced Notes [click to expand]
Chemical reaction is a process in which one substance is chemically converted to another. All chemical reactions involve the formation or destruction of bonds between atoms. Chemical reactions include the rusting of iron and the digestion of food. Most chemical reactions give off heat. For example, chemical reactions that occur in digestion give off heat that keeps our bodies warm and functioning.
Chemists use chemical equations to express what occurs in chemical reactions. Chemical equations consist of chemical formulas and symbols that show the substances involved in chemical changes. The chemical reaction for the rusting of iron shows that four atoms of solid iron react with three molecules of oxygen gas to form two units of solid rust. Experiments demonstrate that iron and oxygen react in these proportions in air at room temperature. Rust is the product, or result, of the reaction. Iron and oxygen are the reactants. The reactants are the substances that undergo chemical change.
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