Honors High School Chemistry

Question

What is the mass of CO2 (carbon dioxide) and H2O (water) formed from the reaction of 1 mole each of n-pentane, n-hexane, n-heptane, and n-octane with an excess of O2 (oxygen gas)? Assume 100% conversion.

Answer 1

I will provide you with the balanced equations for the combustion of each hydrocarbon, and will do the first calculation. I'll leave the others for you to do the same way. Simply use the mole ratios of CO2 and H2O to the hydrocarbon.

n-pentane = C₅H₁₂

C₅H₁₂ + 8O₂ ==> 5CO₂ + 6H₂O ... balanced equation

Calculation:

1 mol C₅H₁₂ x 5 mol CO₂ / 1 mol C₅H₁₂ x 44 g CO₂ / mol CO₂ = 220 g CO₂

1 mol C₅H₁₂ x 6 mol H₂O / 1 mol C₅H₁₂ x 18 g H₂O / mol H₂O = 108 g H₂O

n-hexane = C₆H₁₄

2C₆H₁₄ + 19O₂ ==> 12CO₂ + 14H₂O ... balanced equation

n-heptane = C₇H₁₆

C₇H₁₆ + 11O2 ==> 7CO2 + 8H2O ... balanced equation

n-octane = C₈H₁₈

2C₈H₁₈ + 25O₂ ==> 16CO₂ + 18H₂O ... balanced equation