Percent yield Chemistry

Question

Liquid hexane CH3CH24CH3 reacts with gaseous oxygen gas O2 to produce gaseous carbon dioxide CO2 and gaseous water H2O. If 5.11g of water is produced from the reaction of 7.76g of hexane and 50.3g of oxygen gas, calculate the percent yield of water.

Round your answer to 3 significant figures.

Answer 1

Hexane = CH₃(CH₂)₄CH₃ and not CH₃CH₂₄CH₃ Be careful how you write your questions.

Hexane can also be written as C₆H₁₄

Balanced equation for combustion of hexane:

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

Find limiting reactant:

mols C₆H₁₄ = 7.76 g x 1 mol / 86.2 g = 0.0900 mols (÷2->0.045) = LIMITING REACTANT

mols O₂ = 50.3 g x 1 mol / 32 g = 1.57 mols (÷19->0.083)

Since C₆H₁₄ is the limiting reactant, we use 0.0900 mols of this to determine theoretical yield of H₂O

0.0900 mols C₆H₁₄ x 14 mols H₂O / 2 mols C₆H₁₄ = 0.630 mols H₂O

0.630 mols H₂O x 18 g / mol = 11.34 g H₂O

Percent yield:

5.11 g / 11.34 g (x100%) = 45.1%