Calorimetry is the measurement of the amount of heat evolved or absorbed in a chemical reaction, change of state, or formation of a solution.

We know that heat flows from a hot substance to a cold substance. In Calorimetry, a hot substance and a cold substance are mixed together. The hot substance loses heat to the cold substance until their temperatures are equalized.

According to law of conservation of energy, heat lost by the hot substance = heat gained by the cold substance. This is the principle of calorimetry.

Let m1= mass of the hot substance

t1= temperature of the hot substance

m2= mass of the cold substance

t2= temperature of the cold substance.

S1and S2= specific heats of the hot and the cold substance respectively.

t3= common temperature reached.

Heat lost by hot substance = mass x specific heat x decrease in temperature.

= m1s1(t1-t3)

Heat gained by the cold substance = mass x specific heat x increase in temperature

= m2s2(t3-t2)

According to the principle of calorimeter,

heat lost by hot substance = heat gained by cold substance.

m1s1(t1-t3) = m2s2(t3-t2)

If we know the specific heat of one of the substances, by experimentally measuring all other quantities, specific heat of the given substance can be measured.

Thanks & Regards

Saurabh Singh,

askIITians Faculty

B.Tech.

IIT Kanpur