Specific Heat Capacity for solids
- Consider there are N atoms in a solid. Each atom can oscillate about its mean position.
- Therefore vibrational degree of freedom = kBT
- In one-dimensional average energy=kBT, in three-dimensional average energy =3KBT
- Therefore total internal energy (U) of 1 mole of solid = 3KBTxNA= 3RT
- At constant pressure, ΔQ = ΔU + PΔV change in volume is very less in solids .Therefore ΔV = 0.
- =>ΔQ = ΔU
- CP=(dQ/dT)Vas ΔQ = ΔU, Therefore CV=dU/dT=3R
- Therefore CP=CV=3R