In order to find the number of moles of H2O, we have to use its molar mass, which is 18 grams per each mol of H2O, and also we use the given mass in the question, 97.3 grams:
18 grams = 1 mol
97.3 grams = x moles of H2O
18x = 97.3
x = 97.3/18
x = 5.4 moles of H2O in 97.3 grams
