Question

Q) The combustion of 3.07 g of hydrogen in a bomb calorimeter with a heat capacity of 26.24 kJ/K results in a rise in temperature from 18.43 °C to 35.02 °C. Calculate the heat of combustion (in kJ/g) of the hydrogen. Report your answer to three significant figures.

Please show your work and equations. Thank you!

Answer 1

3.07 g of hydrogen is being burned in a bomb calorimeter.

Heat capacity of the calorimeter = C = 26.24 kJ/K. It means it takes 26.24 kJ of energy to raise the temperature of bomb calorimeter by 1 K.

Initial temperature of the bomb calorimeter,

Final temperature of the bomb calorimeter,

Hence, the rise in temperature can be calculated as

Hence, the energy released by the burning has raised the temperature by 16.59 K can be calculated as follows:

Hence, 435.3216 kJ of energy is released when 3.07 g of hydrogen burns. Hence, the heat of combustion when 1 g of hydrogen burns can be calculated as

Hence, the heat of combustion of hydrogen is 142 kJ/g. (Rounded to three significant figures)

Note: sometimes the heat of combustion is written with a negative sign to signify energy being released by combustion.