When a 3.80-g sample of liquid octane (c8h18) is burned in a bomb calorimeter, the temperature of the calorimeter rises by 27.3 °c. the heat capacity of the calorimeter, measured in a separate experiment, is 6.18 kj> °c. determine the δe for octane combustion in units of kj> mol octane?

Answer is:  the δe for octane combustion is -5112.42 kJ/mol.

Chemical reaction: C₈H₁₈ + 25/2O₂ → 8CO₂ + 9H₂O.

m(C₈H₁₈) = 3.80 g; mass of octane.

n(C₈H₁₈) = m(C₈H₁₈) ÷ M(C₈H₁₈).

n(C₈H₁₈) = 3.8 g ÷ 114 g/mol.

n(C₈H₁₈) = 0.033 mol; amount of octane.

cp= 6.18 kJ/°C, specific heat capacity of the bomb calorimeter.  

Qcal = ΔT · cp.  

Qcal = 27.3°C · 6.18 kJ/°C.  

Qcal = 168.71 kJ; amount of heat absorbed.  

ΔE = Qcal ÷ n(C₈H₁₈).

ΔE = 168.71 kJ ÷ 0.033 mol.

ΔE = 5112.42 kJ/mol.

d.) the average kinetic energy of the gas particles is greater in container b because its particles move faster.

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