How many grams of water are produced when 2.5 mil oxygen reacts with hydrogen?

When 2.5 moles of oxygen react with hydrogen, they react in a 1:2 ratio to produce water. Therefore, 2.5 moles of oxygen will produce 5 moles of water. To convert moles to grams, you'll need to know the molar mass of water, which is approximately 18 grams/mol. So, 2.5 moles of oxygen will produce 90 grams (5 moles x 18 grams/mole) of water.