Answer : S=1.34 KJ
The complete question is -
When 0.7521 g of benzoic was burned in a calorimeter containing 1000 g of water, a temperature rise of 3.60C was observed. What is the heat capacity of the bomb calorimeter, excluding water? The specific heat of water is 4.184 J/g-C and the heat of combustion of benzoic acid is 26.42 kJ/g.
On using the formula of [tex] Q_{rxn} = mSt[/tex], where m is mass of benzoic acid and S is specific heat and t is temperature, we ignore S at this stage.
on solving we get, [tex] Q_{rxn}[/tex] = 0.7521 X 26.42 = 19.870 KJ
We know, [tex] Q_{rxn}[/tex] =[tex] Q_{calorimeter}[/tex] + [tex] Q_{water}[/tex]
Sp. heat of water is 4.184 J,
Here [tex] Q_{water}[/tex] = 1000 X 4.184 X 3.6 = 15062.4 J
on multiplying [tex] Q_{rxn}[/tex] X 1000 to convert into J = 19870.42 J
on substituting the values we get, 19870.482 = 15062.4 + [tex] Q_{calorimeter}[/tex],
hence, [tex] Q_{calorimeter}[/tex]= 4808.082,
Substituting in [tex] Q_{rxn}[/tex] , we get, 4808.082=St ...(ignoring mass as we changed it to J)
t = 3.6, hence we get, S=1335 J/C on dividing by 1000 we get, S=1.34 KJ
