In order to find the mass of 9 moles of aluminium, we have to use its molar mass, which is 26.98 g/mol, that means that in each mol of aluminium we have 26.98 grams of it. Now with 9 moles we can find the result doing a simple calculation:
26.98 g = 1 mol
x grams = 9 moles
x = 242.82 grams of Aluminium in 9 moles
