## Problem 3.16

(a) Determine the chemical formula of the product formed when the metallic element calcium combines with the nonmetallic element oxygen, O2. Write the balanced chemical equation for the reaction.

This is a pretty classic case of a combination reaction (2 reactants --> 1 product). Also, to predict the product, we recognize that a reaction between a metal and a nonmetal gives a salt. Ca forms the +2 ion, and oxygen forms a -2 ion, so the formula of the product is CaO. The balanced equation is

2Ca(s) + O2(g) --> 2CaO(s)

remember that oxygen exists as a diatomic gas, and ionic compounds tend to be solids!

(b) What products form when a compound containing C, H and O is completely combusted in air? Write a balanced chemical equation for the combustion of acetone, C3H6O(l), in air.

Combustion of a compound containing only C, H, and O involves the reaction between the compound and oxygen to form CO2(g) and H2O(l). This is a definition that you should know! So, for the combustion of acetone in air (the air is the source of the oxygen),

C3H6O(l) + 4O2(g) --> 3CO2(g) + 3H2O(l).