Question

calculate the change in internal energy of a block of copper of mass 200g when it is heated from 25 degree Celsius to 75 degree Celsius.Take specific heat of copper equal to 0.1 cal per gram per degree Celsius.and assume the change in volume as negligible..

Answer 1

From 1st law of thermodynamics:

dQ = dU + dW = dU + PdV

Since the change in volume is negligible, dV = 0.

Thus, dU = dQ = m*c*(T2 – T1) = 200 g*0.42 J/g/C*(75-25) = 200*0.42*50 = 4200 J