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

Explanation

The technique of measuring heats of reactions is called calorimetres. The apparatus used is calorimeter.
Calorimeter is a vessel properly insulated and contains water as the calorimetric liquids
A combustioble substance is burnt in oxygen.
Heat evolved during the reaction is measured from the rise in temperature.
Here there is no worke done as `triangleV= 0`
By the raise of temperature of water bath and calorimeter the amount of heat evolved can be determined.
Internal Enegy `triangleU= Q. trianglett xx M/m , Q=" heat capacity"`
`trianglet=t_(2)-t_(1)`
M=Molar mass of substance
m=mass of the substance