To prevent a condition called the “bends”, deep sea divers breathe a mixture containing, in mole percent, 10.0% o2, 10.0% n2 , and 80.0% he.. a. calculate the molar mass of this mixture.. b. what is the ratio of the density of this gas to that of pure oxygen?

The molar mass of the mixture is the summation of the molar mass of a compound in a mixture to its respective molar mass. In this case, 0.10*32 g/mol added to 0.10*28 g/mol and 0.80 *4 g/mol is equal to 9.2 g/mol. The density ratio of the gas to pure oxygen is the ratio of the molar mass between the two, hence 9.2/32 is 0.2875.