Chemistry: First principle of thermodynamics

Click For Summary

Discussion Overview

The discussion revolves around the first principle of thermodynamics, specifically in the context of a homework problem involving heat transfer and work done in a thermodynamic process. Participants analyze the implications of given values and the correctness of multiple-choice options related to the problem.

Discussion Character

  • Homework-related

Main Points Raised

  • One participant calculates the change in energy using the equation E=q+w and concludes that the process is endothermic based on their calculation.
  • Another participant challenges the interpretation of the heat flow, stating that a negative q indicates heat flows from the system to the surroundings, suggesting that option "a" is not false.
  • A participant questions the reasoning behind the conclusion that the process is endothermic based on the calculated energy change.
  • Some participants assert that if option B is false, then the energy change E must also be false, indicating a potential contradiction in the options provided.
  • Repeated emphasis on the impossibility of only option B being false without affecting the validity of E.

Areas of Agreement / Disagreement

Participants express disagreement regarding the truth values of the multiple-choice options, particularly options A and B, and whether the conclusion about the endothermic nature of the process is justified. The discussion remains unresolved with competing interpretations.

Contextual Notes

Participants rely on specific interpretations of thermodynamic principles and the implications of the signs of q and w, which may depend on definitions and assumptions not fully articulated in the discussion.

yecko
Gold Member
Messages
275
Reaction score
15

Homework Statement


1ca04ddf7c25f6c63e307720c34a4ff3.png

https://holland.pk/uptow/i4/1ca04ddf7c25f6c63e307720c34a4ff3.png

Homework Equations


First principle of thermodynamics: E=q+w

The Attempt at a Solution


E=q+w=-17+21=4kJ>0
∴Endothermic (absorb heat from surrounding)

(a) false (from surrounding to the system)
(b) false (does work by surrounding)
(c) true
(d) true

the answer states only option b is false... why option a is true?
Thank you very much!
 
Physics news on Phys.org
q=-17 kJ means that heat flows from the system to the surroundings. So "a" is not false.

And why are you using E=q+w=-17+21=4kJ>0 to say that
∴Endothermic (absorb heat from surrounding)?
 
I see. thanks.
 
It is impossible for only option B to be false. If B is false E is also false.
 
  • Like
Likes   Reactions: DrClaude
mjc123 said:
It is impossible for only option B to be false. If B is false E is also false.
Good catch.
 

Similar threads

  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
4
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 0 ·
Replies
0
Views
2K
Replies
3
Views
6K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
9
Views
3K