State Functions / State Variables

Click For Summary

Discussion Overview

The discussion focuses on the concept of state functions and state variables in thermodynamics, exploring their definitions, characteristics, and examples. Participants seek clarification on the nature of state functions and how they differ from other types of functions, particularly in relation to path dependence.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant defines a state function as properties of a system that are independent of its history, suggesting that these values can be determined solely from the current state.
  • Another participant emphasizes that a state function is path independent, indicating that the process taken to reach a state does not affect the function's value.
  • A request for an example is made to further clarify the concept of state functions.
  • A participant provides an example of enthalpy as a state function, stating that knowing the temperature and pressure allows one to determine enthalpy regardless of how those conditions were achieved. They contrast this with work, which they claim is not a state function because it depends on the path taken between states.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding state functions, with some seeking clarification and examples. There is no consensus on the definitions or implications of state functions, as participants present differing views on the examples and characteristics.

Contextual Notes

Some assumptions about the definitions of state functions and their implications may be missing, and the discussion does not resolve the nuances between different types of functions in thermodynamics.

luckymango
Messages
7
Reaction score
0
State function - Properties of the system that are independent of the history of the system. The values of these variables can be calculated from knowledge of the present state of the system, without knowing its history.

Can someone clarify that?? I'm not getting what a state function is...
 
Science news on Phys.org
A state function means it is path independent. It does not matter how you get there.
 
Can you explain using an example?? Sorry for the hassle...
 
enthalpy is a state function: if you know the temperature and pressure you know the enthalpy. It does not matter how you get to that temperature and pressure.

Work, on the other hand is not a state function. The intergral of the work does not depend on the end conditions, but on the path between those end conditions.

http://en.wikipedia.org/wiki/State_function
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
2K
Replies
5
Views
1K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 57 ·
2
Replies
57
Views
9K