The mass of water is 18.00 grams per mole. What is the % of oxygen in water? Chemistry The Mole Concept Percent Composition 1 Answer anor277 May 26, 2018 %Oby mass=89% Explanation: We want the mass of oxygenmass of water×100%...and for a molar quantity of water this is... 16.00⋅g⋅mol−118.00⋅g⋅mol−1×100%=88.9%.. Answer link Related questions What is mole percent? Question #e2e8b Question #bc737 Question #bc73b Question #e2e8f Question #b9857 Question #b985b Question #fee41 Question #c5c01 Question #bc73f See all questions in Percent Composition Impact of this question 2194 views around the world You can reuse this answer Creative Commons License