# Boundary and P-V diagrams

1. Jun 24, 2014

### mubz09

4m3 rigid tank contains saturated H2O vapour at 3.5 bar. When this tank is left for a long time in a laboratory at 25.4oC, its temperatures reduces to this temperature. The thermodynamic properties of H2O is attached.

Questions

What would the boundary of the system be and what would the P-V diagram be?
Also how would you find the initial temperature and the final pressure?

2. Jun 24, 2014

### SteamKing

Staff Emeritus
What are the conditions for saturated water vapor at a pressure of 3.5 bar? Use yer thermo properties of H2O to find out this info.

What happens to water vapor when it cools below its saturation temperature?

3. Jun 24, 2014

### mubz09

Sorry we were given a table I forgot to add it

#### Attached Files:

• ###### Properties of Water Steam - Table.pdf
File size:
541.4 KB
Views:
86
4. Jun 28, 2014

### BvU

Hello Mubz, and welcome to PF.
Did you notice the omnipresence of the template ? Use it or else...
It's there for good reasons - read the guidelines.
We poor potential helpers are threatened with doom if we help those who don't use it - yet another good reason to use the template.

If you don't understand the above, take it for true on my authority.

Now to business, but only if you solemnly promise to ... use the template!

Nice table. His (her?) vaporative majesty's post and yours must have crossed. Doesn't take much to find an answer to his (/her) first question, right ?

To work out the original exercise, you will need to make a few complementary assumptions (at least, if they weren't already part of the formulation thereof):
1. "a rigid tank" is a closed vessel of fixed shape (does not deform under outside pressure)
2. "contains ..." means "contains ... and nothing else".

You will also need some relevant equations, but for the first part of the first question common sense is enough already. Here (and only here) you get away without equations.
Now item 3 from the template jumps in automatically: what choices do you have and which choice would be your best guess ?

Further help forthcoming - provided you catch up on this template stuff. Would have saved you (and me too) a lot of time if you had used it from the start! And there's another good reason to use the template!

Don't tell me you don't know what to do with the given table after reading the first line of the exercise. I will simply not believe it.

Afterward you can share your thoughts on why they threw in page 2 too. I can't find a reasonable explanation...