Question

5 g of a gas is contained in a rigid container and is heated from 15°C to 25°C. Specific heat capacity of the gas at constant volume is 0.172 cal/g-°C and the mechanical equivalent of heat is 4.2 J/cal. Calculate the change in the internal energy of the gas.

Answer 1

m = 5 g, Δt = 25 – 15 = 10°C
C_V = 0.172 cal/g-°CJ = 4.2 J/Cal.
dQ = du + dw
Now, V = 0 (for a rigid body)
So, dw = 0.
So dQ = du.
Q = msdt = 5 × 0.172 × 10 = 8.6 cal = 8.6 × 4.2 = 36.12 Joule.