Answer :
S=1.34 KJ
The complete question is -
<span>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.
</span>
On using the formula of
![Q_{rxn} = mSt](https://tex.z-dn.net/?f=%20Q_%7Brxn%7D%20%3D%20mSt)
, 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,
![Q_{rxn}](https://tex.z-dn.net/?f=%20Q_%7Brxn%7D)
= 0.7521 X 26.42 = 19.870 KJ
We know,
![Q_{rxn}](https://tex.z-dn.net/?f=%20Q_%7Brxn%7D)
=
![Q_{calorimeter}](https://tex.z-dn.net/?f=%20Q_%7Bcalorimeter%7D)
+
![Q_{water}](https://tex.z-dn.net/?f=%20Q_%7Bwater%7D)
Sp. heat of water is 4.184 J,
Here
![Q_{water}](https://tex.z-dn.net/?f=%20Q_%7Bwater%7D)
= 1000 X 4.184 X 3.6 = 15062.4 J
on multiplying
![Q_{rxn}](https://tex.z-dn.net/?f=%20Q_%7Brxn%7D)
X 1000 to convert into J = <span>19870.42 J
on substituting the values we get, </span>19870.482 = 15062.4 +
![Q_{calorimeter}](https://tex.z-dn.net/?f=%20Q_%7Bcalorimeter%7D)
,
hence,
![Q_{calorimeter}](https://tex.z-dn.net/?f=%20Q_%7Bcalorimeter%7D)
= <span>4808.082,
</span>Substituting in
![Q_{rxn}](https://tex.z-dn.net/?f=%20Q_%7Brxn%7D)
, 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