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's Note .
Chemical reaction is a process in which one substance is chemically converted to another.
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.