Question

A major component of gasoline is octane. When liquid octane is burned in air it reacts with oxygen gas to produce carbon dioxide gas and water vapor. Calculate the moles of octane needed to produce 2.40 mol of water. Be sure your answer has a unit symbol, if necessary, and round it to 3 significant digits.

Answer 1

0.267 mol

Step-by-step explanation:

The unbalanced equation for the reaction that takes place is:

• C₈H₁₈ + O₂ → H₂O + CO₂

Once we balance it we're left with:

• 2C₈H₁₈ + 25O₂ → 18H₂O + 16CO₂

Using the stoichiometric ratio of water and octane from the balanced reaction, we can convert mol of water into mol of octane:

• 2.40 mol H₂O *
  `(2molC_8H_(18))/(18molH_2O)` = 0.267 mol C₈H₁₈

Thus 0.267 moles of octane are needed to produce 2.40 mol of water.