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gnition wires heat sample Thermometer Stirrer A bomb calorimeter, or a constant

ID: 549779 • Letter: G

Question

gnition wires heat sample Thermometer Stirrer A bomb calorimeter, or a constant volume calorimeter, is a device often used to determine the heat of combustion of fuels and the energy content of foods. In an experiment, a 0.4935 g sample of nonanedioic acid (C9H1604) is burned completely in a bomb calorimeter. The calorimeter is surrounded by 1.092x10 g of water. During the combustion the temperature increases from 26.67 to 29.09 C. The heat capacity of water is 4.184 Jgl°c-1 Water The heat capacity of the calorimeter was determined in a previous experiment to be 779.3 J/OC Assuming that no energy is lost to the surroundings, calculate the molar heat of combustion of nonanedioic acid based on these data. CoH1604(s) + 1102(g)8H20()+9 Co2(g)+Energ Insulated Sample ng dish Burning Steel sample outside chamber bomb Molar Heat of Combustion = kJ/mol Combustion (bomb) calorimeter

Explanation / Answer

Q1

m = 0.4935 g of acid

mol = mass/MW = 0.4935/188 = 0.002625 mol

dT = 29.09 - 26.67 = 2.42 °C

Qsystem = m*C*dT + Ccal*dT

Qsystem = (m*C + CCal) * DT = ((1.092*10^3)*4.184 + 779.3)* (2.42) = 12942.71

Qrxn = -Qsystem

Qrxn = -12942.71 J

HRxn = Qrxn/mol = -12942.71 /0.002625

HRxn = -4930556.19 J/mol

HRxn = -4930.56 kJ/mol