Question

What is the heat capacity of the calorimeter, Calorimeter, (in kJ/oC) of a bomb calorimeter if burning 1.0 g of benzoic acid in it causes the temperature to rise by 7.25 oC? Given ΔHcomb = LaTeX: -−26.38 kJ/g.
Answer Choices:

3221.53

3.64

191.26

25.34

-3.64

Answer 1

Answer: The heat capacity of calorimeter is 3.64 kJ/°C

Explanation:

To calculate the heat released, we use the equation:

$\Delta H_{rxn}=\frac{q}{m}$

where,

q = amount of heat released = ? kJ

m = mass of benzoic acid = 1.0 grams

$\Delta H_{rxn}$ = enthalpy change of the reaction = -26.38 kJ/g

Putting values in above equation, we get:

$-26.38kJ/g=\frac{q}{1.0g}\\\\q=(-26.38kJ/g\times 1.0g)=-26.38kJ$

Heat released by the reaction will be equal to the heat absorbed by the calorimeter

Sign convention of heat:

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

To calculate the heat absorbed by the calorimeter, we use the equation:

$q=c\Delta T$

where,

q = heat absorbed = 26.38 kJ

c = heat capacity of calorimeter = ? kJ/°C

$\Delta T$ = change in temperature = 7.25°C

Putting values in above equation, we get:

$26.38kJ=q\times 7.25^oC\\\\q=\frac{26.38kJ}{7.25^oC}=3.64kJ/^oC$

Hence, the heat capacity of calorimeter is 3.64 kJ/°C