Question

Use the following information to answer the questions that follow:
C_(S) + O_2(g) → CO_2(g)      ΔH = -393KJ/mol
H_2(g) + ½O_2(g) → H₂O_(g)     ΔH = -296KJ/mol
C₄ H₁₀ + ¹³/₂O_2(g) →4CO_2(g)+ 5H₂O ΔH = -2877KJ/mol

1. Draw an energy cycle diagram relating heat of formation and combustion of butane. 
2. Calculate the heat of formation of butane.

Answer 1

1. Draw an energy cycle diagram relating heat of formation and combustion of butane. 
2. Calculate the heat of formation of butane. 
   ΔH₁ - ΔH₃ = ΔH₂
   ΔH₁ = 4(-393) + 5(-286)
   = -1572 – 1430
   ΔH₂ = -3002 - -2877 = -125KJ/mol