Question: how many moles of oxygen in h2o?
Answer: Mass of 1 Mole of Water Water (H2O) is made from 2 atoms of hydrogen and 1 atom of oxygen. A mole of water molecules would be 2 moles of hydrogen atoms plus 1 mole of oxygen atoms. From the periodic table we see the atomic weight of hydrogen is 1.0079 and the atomic weight of oxygen is 15.9994.