Internal Energy: Evaporation & 1st Law of Thermodynamics

Click For Summary

Discussion Overview

The discussion revolves around the concept of internal energy, particularly in the context of water evaporation and its relation to the first law of thermodynamics. Participants explore the implications of heating water on internal energy and molecular interactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant seeks an explanation of internal energy and its change during water evaporation, referencing the first law of thermodynamics.
  • Another participant provides links to Hyperphysics as a resource for understanding internal energy and related concepts.
  • A participant mentions that heating water involves breaking potential energy bonds, suggesting this would decrease the internal energy of the system.
  • A later reply challenges this view, stating that breaking molecular bonds increases potential energy, which in turn increases internal energy.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between potential energy and internal energy during the heating of water, indicating that the discussion remains unresolved.

Contextual Notes

The discussion includes references to specific concepts in thermodynamics, such as the nature of potential energy in molecular interactions, which may depend on definitions and interpretations that are not fully clarified.

chocofingers
Messages
30
Reaction score
0
hi,
Can anybody explain the phenomenon behind internal energy? and what is the change in internal energy when water evaporates. Please do give reference to first law of thermodynamics.
Thanks in advance.
 
Science news on Phys.org
chocofingers said:
hi,
Can anybody explain the phenomenon behind internal energy? and what is the change in internal energy when water evaporates. Please do give reference to first law of thermodynamics.
Thanks in advance.
Welcome to Physics Forums.

Hyperphysics is generally a pretty good reference for elementary concepts in physics. Here are the appropriate links:

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/intengcon.html#c1
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/inteng.html
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/phase.html#c3
 
Thank you for the references.
here one of the references says that molecular attractive forces are associated with internal energies also. SO heating water means breaking potential energy bonds and hence decreasing potential energy of the system.thereby the internal energy of the system would reduce ??
 
chocofingers said:
Thank you for the references.
here one of the references says that molecular attractive forces are associated with internal energies also. SO heating water means breaking potential energy bonds and hence decreasing potential energy of the system.thereby the internal energy of the system would reduce ??
No. In this case, the potential energy is a negative quantity, analogous to gravitational potential energy. Therefore, breaking molecular bonds increases the potential energy and hence increases the internal energy.

See the section entitled "Why is the Potential Energy Negative?" on this page: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/phase.html#c3
 
Thankyou sir! I was lingering over this topic since ages and got it NOW!
Thanks :)
 

Similar threads

  • · Replies 10 ·
Replies
10
Views
3K
Replies
5
Views
852
Replies
1
Views
1K
  • · Replies 23 ·
Replies
23
Views
3K
  • · Replies 46 ·
2
Replies
46
Views
6K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 37 ·
2
Replies
37
Views
5K
  • · Replies 32 ·
2
Replies
32
Views
4K