Stoiciometry

Question

If 12.0 g of hydrogen gas reacts with 15.0 g of oxygen gas to form water, what is the maximum amount of water that
can be formed?

Answer 1

2 H₂ + O₂ ---> 2 H₂O
12.0 g of H₂ is 6 moles (12g x (1 mol/2g))
15.0 g of O₂ is 0.9375 mole (15g x (1 mol/16g))

In this case, the oxygen gas is the limiting reactant (the reactant that is completely consumed in a chemical reaction because it determines (or limits) the amount of product formed). The maximum amount of water that can be formed with 15g of Oxygen (0.9375 mole) as the limiting amount would be (0.9375 mole) of water. Convert that to grams.
There are 18g of water per mole (16+2x1).
So 0.9375 moles x (18g/mol) of water = 16.875 or 16.9 g of water