When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 24.0 g of carbon were burned in the presence of 82.9 g of oxygen, 18.9 g of oxygen remained unreacted. What mass of carbon dioxide was produced?

88 g of CO₂ were produced by this reaction

Explanation:

We determine the combustion:

C (s) + O₂ (g) → CO₂ (g)

If the problem states, that oxygen has remained after the reaction is complete, the O₂ is the excess reactant and the limiting.

We convert mass to moles → 24 g. 1mol / 12g = 2 moles

As ratio is 1:1, 2 moles of C must produce 2 moles of CO₂

We convert the moles to mass:

2mol. 44g / 1mol = 88 g