Question

The balanced equation for the synthesis of water is:

2H2 + O2 > 2H2O

If I have 5.5 grams of water, at least how many grams of Oxygen gas was needed?

Answer 1

I believe the answer is 2.75grams of Oxygen Gas

Answer 2

H2O = 18 g/mol
so I have 5.5/18 mols water

you get two mols H2O for every mol of O2

so I used 5.5/36 mols O2
O2 = 32 g/mol

so
5.5*32/36 = 4.89 grams O2