# I Liquid to gas expansion temperature change in a tank

1. Jun 1, 2017

### PHstud

Hello !

I have troube doing a calculation.

Let's say we have a volume Vi in a tank at a pressure Pi. If I let my tank open, the tank's liquid will start to boil to keep the pressure Pi inside the tank. Now, at the end, I will have a volume Vf in the tank, and still a pressure Pi.
But the temperature of the tank will have dropped (lets consider adiabatic), which formula could I use to find the final Temperature ? (Maybe using energy of phase change?)

Thank you !

2. Jun 4, 2017

### John Dalton

Think logically man,remember Charlie's law stating pressure inversely proportional to temperature.
Please examine whether the substance is volatile or not

3. Jun 4, 2017

### Staff: Mentor

Is this a homework problem?

Do you have a specific problem that you can focus on? The basic relationship, derived from the open system version of the first law of thermodynamics, is that the rate of change of total internal energy within the tank is equal to mass rate of vapor exiting times the enthalpy of the exiting vapor.

4. Jun 4, 2017

### John Dalton

Apologies my man.I have made a mistake.won't do this again.