Entropy of the universe

  • Thread starter gboff21
  • Start date
  • #1
50
0

Homework Statement


Two large reservoirs, H and C, are available: if H is at 900 K and C is at 300 K, what is the
entropy change of the Universe if 100 J of heat are taken from H and added to C?


Homework Equations


ΔS=∫dQ/T

ΔS_universe = ΔS_surroundings + ΔS_system

The Attempt at a Solution



so it's just (-100/900)+(100/300) = 9/2 right? Just checking!
 
Last edited:

Answers and Replies

  • #2
collinsmark
Homework Helper
Gold Member
2,970
1,489

Homework Statement


Two large reservoirs, H and C, are available: if H is at 900 K and C is at 300 K, what is the
entropy change of the Universe if 100 J of heat are taken from H and added to C?


Homework Equations


ΔS=∫dQ/T

ΔS_universe = ΔS_surroundings + ΔS_system

The Attempt at a Solution



so it's just (-100/900)+(100/200)
I think that's the right approach. But isn't C at 300 K (not 200)?
= 9/2 right? Just checking!
I think you might have inverted something.
 
  • #3
50
0
Sorry that 200 has been corrected to 300
 
  • #4
collinsmark
Homework Helper
Gold Member
2,970
1,489
Sorry that 200 has been corrected to 300

Okay, so we have...

so it's just (-100/900)+(100/300)

Okay, that looks correct. :approve:

= 9/2 right?
Wait, what?

Try that simplification one more time. :wink:
 
  • #5
50
0
Sorry it's 2/9
 

Related Threads on Entropy of the universe

  • Last Post
Replies
4
Views
1K
Replies
6
Views
30K
  • Last Post
Replies
4
Views
3K
Replies
0
Views
3K
Replies
2
Views
6K
Replies
11
Views
2K
Replies
10
Views
3K
Replies
3
Views
583
Top