By the reaction of carbon & oxygen, a mixture of CO & CO2 is obtained. What is the composition by mass of the mixture obtaind when 20 grams of O2 reacts with 12 grams of carbon?

M (O₂) = 20g

M (O₂) = 32.0 g/mol

n (O₂) = 20/32.0=0.625 mol

m (C) = 12 g

M (C) = 12.0 g/mol

n (C) = 12/12.0=1.0 mol

2C + O₂ → 2CO

1 mol 0.625 mol 1 mol

0.625-0.5=0.125 mol

2CO + O₂ → 2CO₂

0.250 mol 0.125 mol 0.250 mol

n (CO) = 1 mol - 0.250 mol = 0.750 mol

M (CO) = 28.0 g/mol

m (CO) = 0.750*28.0=21.0 g

n (CO₂) = 0.250 mol

M (CO₂) = 44.0 g/mol

m (CO₂) = 0.250*44.0=11.0 g