A bomb calorimeter, or constant volume calorimeter, is a device often used to de

Question

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. In the laboratory a student bums a 1.09 g sample of L-ascorbic acid (C_6H_8O_6) in a bomb calorimeter containing 1020. g of water The temperature increases from 24.20 degree C to 27.00 degree X. The heat capacity of water is 4.184 J g^-1 degree C^-1. The molar heat of combustion is -2340. kJ per mole of L-ascorbic acid. C_6H_8O_6(s) + 5 O_2 (g) rightarrow 6 CO_2(g) + 4 H_2O(l) + Energy Calculate the heat capacity of the calorimeter.

Explanation / Answer

molar mass of C6H8O6 = (6*12 + 8*1 + 6*16) = 176 g/mol

number of moles of ascorbic acid burni,
n = mass/molar mass
= 1.09/176
= 6.19*10^-3 mol

Heat released,
Q = n*H
= (6.19*10^-3)*2340 KJ
=14.492 KJ
= 14492 J

This heat released raises temperature

Q = mw*cw*T + Ccal*T
14492 = 1020*4.184*(27-24.2) + Ccal*(27-24.2)
14492 = 11949.5 + Ccal*2.8
Ccal = 908 J/oC

Answer: 908 J/oC

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