How many moles of CO2 are emitted into the atmosphere when 17.6 g C8H18 is burned?

Answer 1

17.6 g C₈H₁₈ × (1 mol) / (114.23 g) = 0.154 mol C₈H₁₈

0.154 mol C₈H₁₈ × (8 mol CO₂) / (1 mol C₈H₁₈) = 1.23 mol CO₂

Answer

1.23 moles of CO₂ are emitted into the atmosphere when 17.6 g of C₈H₁₈ are burned

Note

Had you been asked for g of CO₂ you would just multiply by the molar mass of CO₂ to get

1.23 mol CO₂ × (44 g) / (1 mol) = 54.2 g CO₂

Answer 2

We can start by writing a correctly balanced equation.

Assuming complete combustion, we know that one molecule of C₈H₁₈ will become 8 molecules of 8CO₂ because of its chemical formula (8 atoms of carbon per molecule C₈H_18, 1 atom carbon per molecule CO2). We could calculate how much O₂ and H₂O are required, but these are not needed to solve the question.

C₈H₁₈ + __O₂ --> 8CO₂ + __H₂O

In order to calculate the moles of C₈H₁₈ used (the molar mass of C₈H₁₈ is 114g):

17.6 g C₈H₁₈ x 1mol C₈H₁₈ / 114 g C₈H₁₈ = 0.154 moles C₈H₁₈

Thus, since one molecule of C₈H₁₈ will become 8 molecules of 8CO₂, 0.154 mol

0.154 moles C₈H₁₈ x 8 mol CO₂ / 1 mol C₈H₁₈ = 1.23 mol CO₂.

ANSWER: 1.23 mol CO₂ produced.