Answer :

To answer this, you need to know the molar mass of water

H = 1.0 g/mol
O = 16.0 g/mol
H2O (water) = 18.0 g/mol

Just multiply the molar mass by the number of moles to get the mass in grams:

[tex](3.5mol\ H_2O)(\frac{18.0g}{mol})=63.0g\ H_2O[/tex]