The temperature change is 5 °C .
Given that ,
High-purity benzoic acid is used to calibrate bomb calorimeters.
A 1.221g sample burns in a calorimeter .
The calorimeter contains 1.200 kg of water .
Heat capacity of calorimeter is 1365 j/°C
∆H rxn = -3227 kj/mol of benzoic acid
Given Mass of the benzoic acid = 1.221 g
Molecular mass of benzoic acid = 122.12g/mol
122.12 g benzoic acid = 1 mol
1.221 g benzoic acid =1.221/122.12= 0.0099 moles
1 mol of benzoic acid gives energy on combustion =3227kj
0.0099 moles of benzoic acid give energy on combustion
= 3227kj×(0.0099mols)/1 mol =32.2647 kj =32264.7 j
Heat absorbed by the calorimeter
= 1365 j/C ×T
Heat absorbed by water
= m× C× T
= 1200 g( 4.18 j/gC ) ×T
= 5016j/C×T
Thus, the total heat absorbed
= 1365T + 5016T
=6381T
As we know,
heat absorbed by the reaction is equal to the heat given out at the end of reaction,
6381T=32264.7
T= 5.05 deg.C
T= 5 °C
Hence , the temperature change is 5 °C .
Heat capacity :
The amount of heat required to raise the temperature of the reaction by 1°C .
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