Question

The heat of combustion of benzoic acid (C6H5COOH) is -3226 kJ/mol. When 0.919 g of benzoic acid was burned in a bomb calorimeter, the temperature of the calorimeter (including its contents) rose from 22.25 °C to 26.27 °C. What is the heat capacity (calorimeter constant) of the calorimeter?

Answer 1

The heat of combustion of benzoic acid (C6H5COOH) is -3226 kJ/mol. When 0.919 g of benzoic acid was burned in a bomb calorimeter, the temperature of the calorimeter (including its contents) rose from 22.25 °C to 26.27 °C. What is the heat capacity (calorimeter constant) of the calorimeter?

Solution :-

we have heat of combustion of benzoic acid that is -3226 kJ/ mol

and used 0.919 g benzoic acid

so lets calculate the amount of heat given by 0.919 g benzoic acid

0.919 g * 3226 kJ / 122.12 g per mol = 24.28 kJ

Now lets calculate the change in the temperature

Delta T = T2 - T1

            = 26.27 C - 22.25 C

            = 4.02 c

now lets calculate the heat capacity of the calorimeter

C cal = q/delta T

Ccal = 24.28 kJ / 4.02 C

Ccal = 6.04 kJ/ C

or we can also write it in J/ C as

6.04 kJ/C * 1000 J / 1 kJ = 6040 J/C

Therefore the heat capacity of the calorimeter = Ccal = 6.04 kJ/ C or 6040 J/C