If 75.0 grams of water is decomposed into hydrogen and oxygen, how many grams of oxygen should be formed?

Answer 1

2H2O ==> 2H2 + O2
Convert 75.0g H2O to mols. mols = grams/molar mass

Use the coefficients in the equation to convert mols H2O to moles O2.

Convert moles O2 to grams. g = mols x molar mass