The specific heat capacity of a solid in the form of a metal block can be determined by an electrical method and method of mixture.
(1) By Electrical Method
Two holes are bored in as the block, after which the block is weighed. A thermometer and an electrical heater are inserted in each of the holes. A little oil in each hole keeps establishing good thermal contact with the block. The initial temperature of the block is noted and the electrical heater is switched on and current allow flowing for some time until the temperature rises by about 150C. the exact time of flow of a known current is measured with a stop-watch and the initial final temperatures of the metal block are measured by the
thermometer.
Heat supplied by current, H=ivt Jules.
Heat required to raise the temperature of block by 0°C = MCθ
IVt = MCθ
C = IVt/Mθ jkg-1k-1
(2) By Method of Mixture
The solid is in the form of a brass or copper block is sighted, tied to a string and left for some minutes in a beaker of boiling water. The calorimeter together with the stirrer is first weighed empty and re-weighted when it is about two-thirds full of water. The initial temperature of the water is read with the thermometer. After the solid has stayed in the boiling water for about 15 minutes it is quickly transferred into the water in the calorimeter. The calorimeter is covered with the lid; and the water is gently stirred to ensure a uniform distribution of temperature. The highest steady temperature of the mixture is read and recoded.
Mass of solid = M1kg
Mass of calorimeter + stirrer = M2kg
Mass of calorimeter + stirrer + water = M3kg
Initial temperature of water = calorimeter = θ1
Final temperature of mixture = θ2
Temperature of boiling water 100°C
Specific heat capacity of water = 4200Jkg-1k-1
Heat lost by solid = heat gained by water + heat gained by calorimeter and stirrer
M1 x C1 (100-θ2) = (m3-m2) x 4200 x (θ2 – θ1) + M2 x C2 x (θ-θ1)
C1 = (m3-m2) x 4200 x (θ2-θ1) + M2C2 (θ-θ1) / M1(100-θ2)
Initial temperature of A1 = θ
Final temperature of mixture = 10°C
Specific heat cap of A1 = 900Jkg-1k-1
Latent heat of fusion = 336 x 10³j/kg
