Why Do Authors Use γ=γ(P,T) Instead of γ=γ(P,T,V) in Thermodynamics?

[LagrangeEuler]

Thermal coefficient of pressure is defined by
$$\gamma=\frac{1}{P}(\frac{\partial P}{\partial T})_V$$. Why in books authors uses $\gamma=\gamma(P,T)$ and no $\gamma=\gamma(P,T,V)$. Could you explain me this. I am sometimes confused with this dependences in thermodynamics.

 

[Chestermiller]

Thermal coefficient of pressure is defined by
$$\gamma=\frac{1}{P}(\frac{\partial P}{\partial T})_V$$. Why in books authors uses $\gamma=\gamma(P,T)$ and no $\gamma=\gamma(P,T,V)$. Could you explain me this. I am sometimes confused with this dependences in thermodynamics.

From the equation of state, V=V(P,T), so there are really only to independent variables.

 

[LagrangeEuler]

Ok. Thanks. But why not $\gamma=\gamma(T,V)$?

 

[Chestermiller]

Ok. Thanks. But why not $\gamma=\gamma(T,V)$?

That can be done, but it's not as convenient for calculations.

 

[LagrangeEuler]

Thanks.