Question

Show that specific heat of solids C = 3R

Answer 1

Answer:

W.K.T,

        Cp-Cv=R           --------1

Now,

        Cv=dU/dT    (U-internal energy)   -------2

        U=f/2*R*T     (f- degree of freedom)

[So, for solid atom, f=4 ,i.e., 3 for transition and 1 for rotation]

Therefore, U= 4/2*R*T

                    = 2*R*T

Substituting U in eqn 2, we get

       Cv= d/dt (2RT)

       Cv= 2R

Now, substituting Cv in eqn 1, we have

       Cp-Cv= R

       Cp-2R= R

       Cp= R+2R

       Cp= 3R

Hope, this helps you :-)