Question

While deciding the unit for heat, which temperature interval is chosen? Why?

Answer 1

When deciding the unit for heat (which is a calorie), the temperature interval chosen is 14.5^oC-15.5^oC.
We know that the amount of heat released or absorbed by a body is given as `DeltaQ = msDeltaT`
Now, we also know that one calorie is defined as the amount of heat required to raise the temperature of 1 g of water through 1^oC. Thus, for 1 calorie of heat energy, the specific heat capacity of water should be 1 cal g^-1 oC^-1. It is found experimentally that the specific heat capacity of water is 1 cal g^-1 oC^-1 when the temperature range is 14.5^oC-15.5^oC.