Question

When a bomb calorimeter is used to determine the heat of reaction is most likely if the system under investigation is most likely to remain constant?
A) Number of molecules
B) Pressure
C) Temperature
D) Volume

Answer 1

Hint: In general, a calorimeter is used to measure the energies (both absorb and release) that is released during chemical reactions and a bomb calorimeter is a special type of calorimeter

Complete answer:
Heat of reaction is also known as the change in enthalpy whose sign tells about the change in heat taking place in the reaction.
Its positive sign shows that the heat is absorbed during the reaction and it is endothermic while its negative sign shows that the heat is being released during the reaction and it is exothermic
All these changes in energies (along with other changes like temperature) taking place during a reaction are measured using the calorimeter but a bomb calorimeter is a special type of calorimeter that is used to measure this heat of reaction at constant volume i.e for isochoric processes.
We measure the change in internal energy at constant volume using a bomb calorimeter which is equal to the heat of reaction.
So, when the volume is constant all the other physical quantities like temperature, pressure, volume and number of molecules tend to change.
Thus it can be said that when a bomb calorimeter is used to determine the heat of reaction, the volume of the system is most likely to remain constant.
The schematic diagram of a bomb calorimeter is:

Thus the correct option is D).

Note: Bomb calorimeter is an apparatus that can be used to measure the heat of combustion hence is generally used for combustion reactions.
Bomb calorimeter has its own capacity which needs to be taken into consideration while doing calculations.
Isochoric processes are those processes which are undertaken at constant volume