Calculate the internal energy change, Δ_rU, for the combustion of 29.3 g of vitamin C (C₆H₈O₆, molar mass = 176.124 g mol^-1) if the combustion inside a bomb calorimeter, C_cal = 8.31 kJ °C^-1, causes a temperature change from 21.5 °C to 68.3 °C.

Question

Quizplus · Accepted Answer

First, let's calculate the heat released by the combustion of vitamin C: n = 29.3 g / 176.124 g/mol = 0.166 mol (moles of vitamin C) ΔT = 68.3 °C - 21.5 °C = 46.8 °C (temperature change in calorimeter) q = CΔT = 8.31 kJ/mol·°C × 0.166 mol × 46.8 °C = 6.29 kJ (heat released by combustion) Since the reaction occurred inside a bomb calorimeter, the heat released by the combustion is equal to the internal energy change of the system. Therefore: Δ_rU = -6.29 kJ/mol = -2.34 × 10^3 J/mol (convert kJ to J, with 1 kJ = 10^3 J) So, the correct answer is B.

Calculate the Internal Energy Change, ΔrU, for the Combustion of 29.3

Calculate the Internal Energy Change, Δ_rU, for the Combustion of 29.3