Question

When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 27.6 g of carbon were burned in the presence of 84.9 g of oxygen, 11.3 g  of oxygen remained unreacted. What mass of carbon dioxide was produced?

Answer 1

The reaction of carbon combustion (reaction with oxygen ) is

          C(s) + O2(g) --> CO2(g)

One moles of carbon will react with one moles of oxyge to give one moles of CO2

Atomic weight of Carbon = 12g / mole

Molecular weight of O2 = 32g / mole

Molecular weight of CO2 =44g / mole

Therefore 12 grams of carbon will react with 32 grams of oxygen to give 44 grams of CO2

1 gram of carbon will react with 32/12 grams of oxygen to give 44/12 grams of CO2

27.6 gram of carbon will react with = 32 x 27.6 / 12 grams of oxygen = 73.6 grams of oxygen

{oxygen left = 84.9- 73.6 = 11.3 grams)

The mass of CO2 produced = 44 x 27.6 / 12 grams = 101.2 grams of carbon dioxide