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

ID: 549768 • Letter: G

Question

gnition wires heat sample Thermometer Stirrer A bomb calorimeter, or constant volume calorimeter, is a device often used to determine the heat of combustion of fuels and the energy content of foods Since the "bomb" itself can absorb energy, a separate experiment is needed to determine the heat capacity of the calorimeter. This is known as calibrating the calorimeter Water In the laboratory a student burns a 0.519-g sample of quinizarin (C14Ho4 in a bomb calorimeter containing 1050. g of water. The temperature increases from 25.00 C to 27.50 °C. The heat capacity of water is 4.184 J gC loc-1 The molar heat of combustion is -6057 kJ per mole of quinizarin C14HsO4(s) + 14 02(g)14 CO2(g) +4H20(1) + Energy Calculate the heat capacity of the calorimeter. Insulated Sample Burng outside chamber heat capacity of calorimeter = dish sample bomb Combustion (bomb) calorimeter

Explanation / Answer

Q1

m = 0.519 g of quinizarin

mol = mass/MW = 0.519/240.214 = 0.002160

-Qsystem = Qwater + Qcal

-Qsystem = m*C*(Tf-Ti) + Ccal*(Tf-Ti)

-Qsystem = 1050*4.184*(27.5-25) + Ccal*(27.5-25)

Qsystem = n*HRxn = 0.002160 * 6057*10^3

0.002160 * 6057*10^3 = 1050*4.184*(27.5-25) + Ccal*(27.5-25)

13083.12 =   -10983 + Ccal (27.5-25)

13083.12 -10983 =  Ccal (27.5-25)

2100.12 / (27.5-25) = Ccal

Ccal = 840.048 J/C