Chemistry Reference
In-Depth Information
When a chemical reaction releases energy to its environment the
temperature of the environment rises. Such reactions are described
as
exothermic.
In exothermic reactions, heat is released when particle
movement slows and when high-energy bonds between atoms are broken.
Therefore, water freezing to form ice and combustion reactions are both
examples of exothermic reactions. The opposite of exothermic reactions
are
endothermic reactions
, which absorb energy from their environment.
In an endothermic reaction such as the melting of ice, the surrounding
environment loses heat. Chemical reactions that do not occur without
the addition of energy are endothermic. In this experiment, you will
perform endothermic and exothermic reactions, monitor the changes in
temperature that occurs in the surrounding environment, and plot your
results on a graph.
Time Required
25 minutes for Part A
25 minutes for Part B
Materials
2
barium hydroxide octahydrate (solid)
2
ammonium chloride (solid)
2
magnesium metal strips
2
6 molar (M) hydrochloric acid
2
baking soda
2
2 beakers (about 250 milliliters [ml])
2
electronic balance
2
disposable weigh boats
2
small block of wood (slightly larger than the diameter of the
beaker)
2
stirring rod
2
wash bottle filled with distilled water
2
Celsius (C) thermometer
2
hot mitts
2
goggles
