THE SPECIFIC HEAT CAPACITY OF SOME MATERIALS

Substances or materials with small heat specific heat capacity like mercury will warm up faster or quickly and will lose the heat faster or quickly.

Substances with high specific heat capacity will warm up slowly and will lose heat slowly also. Eg Water. Aluminum and silver are used in cooking utensils because they absorb heat faster and that is why it is used in thermometers. The specific heat capacity of water is 4200 J/kgK. I.e. 42000J of energy will raise the temperature of 1kg of water through 1K.

Example: In an experiment to determine the specific heat capacity of water, 5A of current was supplied to 3kg of water in a 240V kettle and the temperature was raised from 20°C to 85°C. Calculate the time taken.

Solution

t=mc(θ2-θ1)IV

But m = 3kg; c = 4200J/kgK,   θ1=20°C ,    θ2=85°C, I = 5A, V = 240V

t= 3*4200*(85-20)5*240=13652=682,5s

Exercise: An electric kettle of mass 0.5kg contains 2kg of water at 27°C. The kettle is rated 2000W. How long would it take the water in the kettle to boil at 100°C, given the specific heat capacity of water is 4200J/kgK while that of the material of kettle is 880J/kgK.