# Homework Help: Finding the internal energy using a steam table

1. May 7, 2015

### smoothie king

1. The problem statement, all variables and given/known data
What is entropy of water at 5 Bar and an internal energy of 2724 kJkg-1?

3. The attempt at a solution
I have looked at the steam tables, i found where the pressure is 500kpa, then i do not know where to go from there.

Thank You

Last edited: May 7, 2015
2. May 7, 2015

### phinds

So you will be supplied with tables that no one has told you how to use? Really?

3. May 7, 2015

### smoothie king

i have changed the question around

Last edited: May 7, 2015
4. May 7, 2015

### smoothie king

sorry for double post, i pressed something wrong by accident.

Last edited: May 7, 2015
5. May 7, 2015

### Staff: Mentor

Let me understand correctly. You have steam tables, and you know that you have water at 5 bars with an internal energy of 2724 kJ/kg, and you are asked to determine its entropy. Is that right?

Chet

6. May 7, 2015

### smoothie king

Yes, thats exactly what i'm trying to do, i didnt know how to change the title and i didnt want to start a new thread.

Last edited: May 7, 2015
7. May 7, 2015

### Staff: Mentor

You found a place in the tables where the pressure is 500 kPa. What is the heading on the top of the page (e.g., saturated steam or superheated steam)?

Chet

8. May 7, 2015

### smoothie king

Superheated Steam

9. May 7, 2015

### Staff: Mentor

OK. Now there are columns of numbers on the page. What are the headings on the columns of numbers?

Chet

10. May 7, 2015

### smoothie king

They are all temperatures from 100°c to 700°c

11. May 7, 2015

### Staff: Mentor

What are the headings on the other columns (or rows?)?

Chet

12. May 7, 2015

### smoothie king

there is t(sat), then h and s for all the temperatures above. also hg and sg for saturation

13. May 7, 2015

### Staff: Mentor

I thought you said that the part of the table you were open to was for superheated steam. This table is for saturated steam. What gives?

Chet

14. May 7, 2015

### smoothie king

i have two tables and i didn't notice, i have one with h and s, another with u and v, i just realized that i have to find the value for temperature in the u and v table using internal energy, then use that temperature to find the value of entropy in the h and s table. I got the value of entropy to be 7.272.

Thank you very much!!!

15. May 7, 2015