Question

0.260 mol of octane is allowed to react with 0.760 mol of oxygen. How many moles of water are produced in this reaction? After the reaction, how much octane is left? Please, use conversion factors if possible.

Answer 1

Answer:

0.5472 moles of H₂O are produced

0.1992 moles of C₈H₁₈ were left

Explanation:

The reaction of octane (C₈H₁₈) with oxygen (O₂) is:

C₈H₁₈ + 25/2 O₂ → 8CO₂ + 9H₂O

Where 1 mole of octane reacts with 25/2 moles of oxygen to produce 8 moles of carbon dioxide and 9 moles of water

For a complete reaction of 0.760moles of oxygen there are needed:

0.760 mol O₂ ₓ (1 mole C₈H₁₈ / 25/2 moles O₂) = 0.0608 moles of C₈H₁₈

As you have 0.260 moles, the moles of octane that were left are:

0.260 mol - 0.0608 mol = 0.1992 moles of C₈H₁₈

Now, if 0.760 moles of O₂ react, the moles of water that are produced are:

0.760 mol O₂ ₓ (9 moles H₂O / 25/2 moles O₂) = 0.5472 moles of H₂O