Question

When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 22.8 g of carbon were burned in the presence of 73.0 g of oxygen, 12.2 g of oxygen remained unreacted. What mass of carbon dioxide was produced?

Answer 1

C + O2 -----> CO2

no of moles of carbon = 22.8/12 =1.9 moles

no of moles of O2    = 73/ 32 = 2.28 moles

no of moles of unreacted = 12.2/32 = 0.38 moles

reacted no of moles = 2.28-0.38 = 1.9 moles

carbon is limiting reagent

From balanced equation

1 mole of carbon react with oxygen to form 1 moles of Co2

1.9 moles of carbon react with oxygen to form 1.9 moles of CO2

mass of CO2 = no of moles of CO2 * Gram molar mass

                   = 1.9*44

                  = 83.6gm of CO2