Answer to Question #174603 in Chemistry for Hamza

Question

The molar enthalpy of reaction of

C₅H₁₂(g) + 8 O₂(g) → 5 CO₂(g) + 6 H₂O(g)

is -3244.8 kJ/mol for C₅H₁₂(g). If 100.0g of oxygen gas react, how much heat is released by the reaction?

Do not include a sign in your answer.

Answer 1

Solution:

The balanced thermochemical equation:

C₅H₁₂(g) + 8O₂(g) → 5CO₂(g) + 6H₂O(g), △H = -3244.8 kJ/mol

The equivalences for this thermochemical equation are:

1 mol C₅H₁₂ ⇔ 8 mol O₂ ⇔ 5 mol CO₂ ⇔ 6 mol H₂O ⇔ -3244.8 kJ

Convert the amount of oxygen gas (O₂) to moles:

(100.0 g O₂) × (1 mol O₂ / 32 g O₂) = 3.125 mol O₂

Use the thermochemical equation to determine the energy change:

(3.125 mol O₂) × (3244.8 kJ / 8 mol O₂) = 1267.5 kJ

Answer: 1267.5 kJ of heat is released by the reaction.