This chapter covers the concept of heat as a form of energy, units of heat, principle of calorimetry, formula of the amount of heat absorbed for a given change in temperature, specific heat capacity and molar heat capacity of a substance, determination of specific heat capacity in laboratory, concepts of latent heat of fusion and vaporization, measurement of specific latent heat of fusion of ice and of vaporization of water, and mechanical equivalent of heat (Searle's Cone Method).
* the energy being transferred between two bodies or between adjacent parts of a body as a result of temperature difference is called heat.
* Heat is a form of enery. It is energy in transit whenever temperature differences exist. Once it is tranferred it becomes the internal energy of the receiving body.
* The amount of heat needed to increase the temperature of 1 g of water from 14.5 degrees Centigrade to 15.5 degrees Centigrade at a pressure of 1 atm is called 1 calorie.
*The calorie is now defined in terms of joule as 1 cal = 4.186 joule.
*Principle of Calorimetry: The total heat given by the hot objects equals th total heat received by the cold objects.
* Heat supplied to the body Q = ms *(change in temperature) where m = mass of the body, s = specific heat capacity of the substance.
* Units of s = Joules per Kg K or Joules per Kg-degrees Centigrade
* If the amount of substance is expressed in the number of moles
Q = nC *(change in temperature) where n is the number of moles in the sample and the constant C is called molar heat capacity.
* the quantity ms is called the heat capacity of the body. Its unit is J/K.
*The mass of water having the same heat capacity as a given body is called the water equivalent of the body.
JEE examination questions
2007 examination: No questions were asked from this chapter.