When 1.14g of octane reacts with excess oxygen in a bomb calorimeter, the temperature of the calorimeter increases by 10.0°C. The total heat capacity of the calorimeter is 6.97 kJ/°C. answer in kJ.

Question

When 1.14 g of octane (molar mass = 114 g/mol) reacts with excess oxygen in a constant volume calorimeter, the temperature of the calorimeter increases by 10.0°C. The total heat capacity of the calorimeter is 6.97 kJ/°C. Determine the energy for the reaction, (q _rxn) in kJ

Answer 1

To answer this question we need to realize a couple things.

Given constant volume the following holds true.

1. q_rxn = -q_calorimeter
2. q_calorimeter = (heat capacity of calorimeter) x (ΔT)

q_cal = (6.97 kJ / ^oC ) x (10 ^oC) = 69.7 kJ

q_rxn = -69.7 kJ

Technically this answers your question but given the information in the question given I assume it probably will ask for the answer in (kJ/mol)

1.14g octane (1mol octane / 114g octane) = 0.01 mol octane

q_rxn (kJ/mol) = (-69.7 kJ) / (0.01 mol octane)

q_rxn = -6970 kJ / mol of octane