What mass of water, in grams, would have to be decomposed to produce 13.3 L of molecular oxygen at STP?

Question

How do I go about doing this problem?

Answer 1

how many moles is that?

n=PV/RT solve that.

Then, each mole of water decomposes to 1/2 mole of oxygen gas. so whatever moles of O2 you found, multipy by two, that is the moles of water, convert that to grams.