- #1
yecko
Gold Member
- 279
- 15
- Homework Statement
- partial differential
- Relevant Equations
- chain rule / quotient rule
From the solution of my thermodynamics homework,
$$
({\frac{\partial h_{fg}/T}{\partial T}})_P \\ = ({\frac{\partial h_{g}/T}{\partial T}})_P - ({\frac{\partial h_{f}/T}{\partial T}})_P = \frac{1}{T} ({\frac{\partial h_{g}}{\partial T}})_P - \frac {h_g}{T^2} - \frac{1}{T} ({\frac{\partial h_{f}}{\partial T}})_P + \frac {h_f}{T^2}
$$
Isn't ##({\frac{\partial h_{g}/T}{\partial T}})_P = \frac {h_g}{T^2} ##?
And ##({\frac{\partial h_{f}/T}{\partial T}})_P = \frac {h_f}{T^2}##
Why is there the other two parts: ##\frac{1}{T} ({\frac{\partial h_{g}}{\partial T}})_P ## and ##- \frac{1}{T} ({\frac{\partial h_{f}}{\partial T}})_P## ?
Thank you