The volume of an unknown amount of CHBrCI 2 was 4.878 L. The volume of 14.20 grams occupies a volume of 8.176 L at the same temperature and pressure? How many grams of the gas were in the first experiment? Key Concept:Avagadro's law states that the volume and number of moles are directly related to each other (V = k*n) and that equal volumes of different gases at the same temperature and pressure contain the same number of molecules.