How many grams of water are produced when 2.50 mol oxygen reacts with hydrogen?

Given:

2.5 mol O2

Required:

Grams of water

Solution:

2H2 + O2 - > 2H2O

Moles of H2O = (2.5 mol O2) (2 moles H2O/1 mole O2) = 5 moles H2O

Molar mass of H2O = 18.02 g/mol

Mass of H2O = (5 moles H2O) (18.02 g/mol)

Mass of H2O = 90.1g H2O