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 carbon"/"Mass of carbon + oxygen"xx100%# Explanation: #"So %C by mass"# #=# #(12.011*g*mol^-1)/((12.011+15.999)*g*mol^-1)xx100%# 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 13264 views around the world You can reuse this answer Creative Commons License