Many chemical reactions give off energy. Chemical reactions that release energy are called exothermic reactions.
Some chemical reactions absorb energy and are called endothermic reactions.
In this lab students studied one exothermic and one endothermic reaction. In Part I, we studied the reaction between citric acid solution and baking soda. In Part II, we studied the reaction between magnesium metal and hydrochloric acid. In this experiment, the cooling and warming behavior of a familiar substance, water, was investigated. By examining graphs of the data, the freezing and melting temperatures of water was determined and compared.