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## Homework Statement

Equation for the substance given for a certain range of pressure and temperature:

v=(RT/p) - C/T

^{3}

Where C=Constant

Show that

(i) The change of enthalpy for this substance in an isothermal process is

(h

_{2}-h

_{1})

_{T}=4C/T

^{3}(p

_{1}-p

_{2})

_{T}

(ii) The change of entropy for this substance in an isothermal process is

(S

_{2}-S

_{1})

_{T}=Rln(p

_{1}/p

_{2})+3C/T

^{4}(p

_{1}-p

_{2})

_{T}

## The Attempt at a Solution

taking h=U+pv

dh=du+d(pv) {du=0 for isothermal process}

dh=d(pv)=-Cdp/T

^{3}

but result which i need to show has factor 4 also; which i have no idea how to get.