Explain the determination of `DeltaU` of a reaction calorimetrically.

Explanation

The change in internal energy `DeltaU` in a chemical reaction can be determined using bomb calorimeter. The bomb is a steel vessel. It is immersed in a water bath. The whole device is called calorimeter.

A combustible substance is burnt in pure oxygen supplied in the steel bomb. The heat evolved during the reaction measured from the rise in the temperature. Since the bomb calorimeter is sealed, the energy changes taking place in it are considered as that taking place at constant volume. Temperature change of the calorimeter produced by the reaction is then converted to `q_v` by using the known heat capacity of the calorimeter.
`q=-CxxM/WxxDeltaT`
where 'C' is the heat capacity of calorimeter
`DeltaT` is the change in temperature
W is the mass of substance
M is the molecular mass of substance taken.