How do you calculate the percentage by mass of carbon in carbon monoxide? Chemistry The Mole Concept Percent Composition 1 Answer anor277 Nov 7, 2016 %C by mass = Mass of carbonMass of carbon + oxygen×100% Explanation: So %C by mass = 12.011⋅g⋅mol−1(12.011+15.999)⋅g⋅mol−1×100% So C≡O, percentage carbon by mass is a bit under 50%. 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 14074 views around the world You can reuse this answer Creative Commons License