The mass of 1.73 moles CaH2 is 72.82 grams. The molar mass of CaH2 is 42.08 g/mol. This means that there are 42.09 grams in 1 mol. So, x grams will be in 1.73 mol of CaH2. Let's make a proportion: 42.09 g : 1 mol = x : 1.73 mol. x = 42.09 g * 1.73 mol : 1 mol. x = 72.82 g.
