Isooctane Is a Good Model Compound for Gasoline

Multiple Choice

Isooctane is a good model compound for gasoline. When 1.14 g of isooctane
(C₈H₁₈, molar mass = 114 g/mol) reacted with excess oxygen in a constant volume calorimeter, the temperature of the calorimeter increased by 5.83°C. The calorimeter consisted of two components: a steel vessel with a heat capacity of 1.00 kJ/ °C and 2.00 L of water surrounding it. The density and specific heat capacity of water are 1.00 g/mL and 4.184 J/(g . °C) , respectively. Use these data to determine the molar enthalpy of combustion of isooctane.

A) -5.83 kJ
B) -54.6 kJ
C) -5,460 kJ
D) -48,800 J
E) -48,800 kJ