When 1.365 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 25.89°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. A) +39.7 kJ/mol B) -39.7 kJ/mol C) -7060 kJ/mol D) -8120 kJ/mol

Question

Quizplus · Accepted Answer

First, calculate the amount of heat absorbed by water:

q = mCΔT = (500.0 g)(4.18 J/(g ∙ °C))(25.89°C) = 54751.7 J = 54.8 kJ

Next, calculate the amount of heat released by the combustion of 1 mole of anthracene:

q = -ΔH = -(54.8 kJ / 1.365 g) * (1 mol / 178.24 g) = -4084 kJ/mol

Note: the negative sign indicates that heat is released by the combustion reaction.

Finally, round the value to the nearest tenth and select the answer closest to it.

Thus, the closest answer is C, which is -7060 kJ/mol.

When 1365 G of Anthracene,C14H10,is Combusted in a Bomb Calorimeter That

When 1365 G of Anthracene,C₁₄H₁₀,is Combusted in a Bomb Calorimeter That