What Does Svante Arrhenius' Salt Water Experiment Reveal About Entropy?

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Discussion Overview

The discussion revolves around the implications of Svante Arrhenius' salt water experiment in relation to entropy, particularly focusing on the behavior of ions in a glass of salt water when an electrical charge is applied. Participants explore the concepts of entropy change and energy interactions within the system.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Bernadette describes the arrangement of ions (Cl- and K+) in salt water when an electrical charge is applied and questions the entropy change associated with this transformation.
  • One participant requests Bernadette to provide relevant equations and her predictions regarding the entropy value in this context.
  • Bernadette expresses uncertainty about the entropy variation, suggesting that while she feels entropy decreases, she acknowledges it is likely impossible.
  • Another participant questions whether energy is being added or subtracted from the system as the electrical charge approaches.
  • Bernadette clarifies that mechanical energy is received as the electrical charges approach, indicating that energy is subtracted from the isolated system.
  • Bernadette further inquires if applying the electric field leads to an increase in order within the system.

Areas of Agreement / Disagreement

The discussion remains unresolved, with participants expressing differing views on the relationship between the application of an electric field, entropy, and energy changes in the system.

Contextual Notes

Participants have not reached a consensus on the entropy variation equation applicable to this transformation, and there are unresolved assumptions regarding the definitions of order and energy in the context of entropy.

Bernadette
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Hello

Sorry for my English...

We approach slowly (in a quasi-reversible way) an electrical charge of a glass of salt water.
Some ions arrange themselves in the glass.

What can we say about entropy of this transformation?

Bernadette

PS: My reflection comes from reading an old physics book (in French...) where an experiment by Svante Aarhenius, the "father" of ions, is described.

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Welcome to PF. :smile:

In the schoolwork forums and the technical forums, we require that you tell us what you think will happen. Can you show us the relevant equations that decsribe the Entropy of this setup, and tell us what you think will happen to the value of the Entropy? Thanks.
 
Hello

As it is showed on the picture, some ions (Cl- and K+) move.
In the sense of Boltmann's statistical physics, we have more order after approaching the charge.
I don't know the entropy variation equation for this transformation, if it exists.
I want to write that entropy decreases but I know it's impossible.

Bernadette
 
Bernadette said:
I want to write that entropy decreases but I know it's impossible.
But is energy being added or subtracted from this system? :wink:

Also, is this for schoolwork? I can move your thread to the schoolwork forums if that is a better match...
 
Hello

We receive mechanical energy as electrical charges approach. So energy is subtracted from this (isolated) system.
It is not a schoolwork. Just asking questions in my mind. I am no more student, (regrets)

From the other side of Atlantic ocean.

Bernadette
 
Hello

No more response?

Can we say that when we apply the electric field (we approach the charge), the order increases?

Have a nice day

Bernadette
 

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