Mothballs are composed primarily of the hydrocarbon naphth alene (C10H8). When 1.025 g of naphthalene burns in a bomb calorimeter, the temperature rises from 24.25∘C to 32.33∘C. Find ΔErxn for the combustion of naphthalene. The heat capacity of the bomb calorimeter, determined in a separate experiment , is 5.11kJ/∘C.

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jean2098 · Accepted Answer

Step 1 The temperature change (ΔT) in a bomb calorimeter is related to the heat absorbed by the entire calorimeter assembly (qcal). qcal=Ccal×ΔT Where Ccal is the heat capacity of the bomb calorimeter. Since no heat escapes the bomb calorimeter. qrxn=−qcal Combining the two equations qrxn=−Ccal×ΔT Step 2 Given that 1.025 g of naphthalene (C10H8) burned in a bomb calorimeter raises the temperature rises from 24.25{∘C to 32.33∘C. Determine the ΔErxn(kJ/mol) for the combustion of naphthalene if the heat capacity of the bomb calorimeter is 5.11kJ/∘C. Recall that ΔErxn=qrxnn ​ Step 3 Solving for qrxn. qrxn=−5.11k{∘}C×(32.33∘C−24.25∘C)=−41.2888kJ Step 4 Solving for nn naphthalene from g naphthalene using molecular weight (MW=128.1705g/mol). 1.025 g biphenyl×1mol128.1705gnaphthalene=7.997×10−3 moles naphthalene Step 5 Solving for ΔErxn ΔErxn=qrxnn=−41.2888kJ7.997×10−3moles naphthalene=−5163kJ/mol≈−5200kJ/mol

Fasaniu · Accepted Answer

Mothballs are composed primarily of the hydrocarbon naphth alene (C

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