Mothballs are composed primarily of the hydrocarbon naphthalene (c10h8). when 1.025 g of naphthalene burns in a bomb calorimeter, the temperature rises from 24.25 °c to 32.33 °c. find ∆erxn for the combustion of naphthalene. the heat capacity of the calorimeter, determined in a separate experiment, is 5.11 kj> °c.

-5.16 × 10³ kJ/mol

Explanation:

According to the law of conservation of the energy, the sum of the heat released by the combustion and the heat absorbed by the bomb calorimeter is zero.

Qcomb + Qcal = 0

Qcomb = - Qcal   [1]

The heat absorbed by the calorimeter (Qcal) can be calculated using the following expression.

Qcal = Ccal . ΔT

where,

Ccal is the heat capacity of the bomb calorimeter

ΔT is the change in the temperature

From [1],

Qcomb = -Qcal = -(5.11 kJ/°C) × (32.33°C - 24.25°C) = -41.3 kJ

Let's consider the molar mass of naphthalene to be 128.17 g/mol. The change in the internal energy (∆Erxn) for the combustion of naphthalene is:

i think it’s a. this is because if they measured the mass of something with a mass of 150g, then their final answer would have to be approximately 150g. though all of their answers are almost 150, rosa and tran have the closest answers (or the exact answer) to the accurate one.