Calculate the amount (mass)of acetaldehyde (C₂H₄O,molar mass = 44.0526 g mol^-1)that causes a bomb calorimeter with a heat capacity of 12.91 kJ °C^-1 to have a temperature increase from 27.8 °C to 41.7 °C.The D_rU for the combustion of acetaldehyde is -1166.9 kJ mol^-1.

Question

Quizplus · Accepted Answer

First, we need to calculate the amount of heat released by the combustion of acetaldehyde using its D_rU value: D_rU = -1166.9 kJ/mol We know that we need to calculate the amount of acetaldehyde that causes a bomb calorimeter with a heat capacity of 12.91 kJ/°C to have a temperature increase from 27.8 °C to 41.7 °C. The heat that caused the temperature increase is: q = C ΔT where q is the heat, C is the heat capacity, and ΔT is the temperature change. Substituting the values, we have: q = (12.91 kJ/°C) x (41.7 °C - 27.8 °C) q = 179.5 kJ We also know that the amount of heat released by the combustion of a certain amount of acetaldehyde is: q = n D_rU where n is the amount (in moles) of acetaldehyde that was burned. Substituting the values, we have: 179.5 kJ = n (-1166.9 kJ/mol) Solving for n, we have: n = -179.5 kJ / -1166.9 kJ/mol n = 0.1536 mol Finally, we can calculate the mass of acetaldehyde using its molar mass: mass = n x molar mass mass = 0.1536 mol x 44.0526 g/mol mass = 6.77 g Therefore, the answer is choice A (6.77 g).

Calculate the Amount (Mass)of Acetaldehyde (C2H4O,molar Mass = 44

Calculate the Amount (Mass)of Acetaldehyde (C₂H₄O,molar Mass = 44