When 0.455 g of anthracene, c14h10, is combusted in a bomb calorimeter that has a water jacket containing 500.0 g of water, the temperature of the water increases by 8.63°c. assuming that the specific heat of water is 4.18 j/(g ∙ °c), and that the heat absorption by the calorimeter is negligible, estimate the enthalpy of combustion per mole of anthracene?

Answer is: enthalpy of combustion per mole of anthracene is -7073.21 kJ/mol.

Balanced chemical rreaction of anthracene combustion:

C₁₄H₁₀ + 33/2O₂ → 14CO₂ + 5H₂O.

m(C₁₄H₁₀) = 0.455 g; mass of anthracene.

ΔT(H₂O) = 8.63°C.

m(H₂O) = 500.0 g; mass of water.

cp = 4.18 J/g·°C; specific heat of water.

n(C₁₄H₁₀) = m(C₁₄H₁₀) ÷ M(C₁₄H₁₀).

n(C₁₄H₁₀) = 0.455 g ÷ 178.23 g/mol.

n(C₁₄H₁₀) = 0.00255 mol; amount of anthracene.

Q = ΔT(H₂O) · m(H₂O) · cp.

Q = 8.63°C · 500 g · 4.18 J/g·°C.

Q = 18036.7 J ÷ 1000 J/kJ.

Q = 18.037 kJ; heat absorb by water.

ΔH = Q ÷ n(C₁₄H₁₀).

ΔH = 18.037 kJ ÷ 0.00255 mol.

ΔH = 7073.21 kJ/mol.

it is the most commonly accepted one