Exploring Entropy with Svante Arrhenius' Salt Water Experiment

In summary, the conversation discusses the concept of entropy in relation to an experiment with an electrical charge of salt water. The speaker reflects on the experiment described in a physics book and raises questions about the entropy variation equation and the effect of energy on the system. They also mention the increase in order when an electric field is applied.
  • #1
Bernadette
29
0
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.

IMG_2001.jpg
 
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  • #2
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.
 
  • #3
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
 
  • #4
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...
 
  • #5
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
 
  • #6
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
 

1. What is entropy and why is it important?

Entropy is a measure of the disorder or randomness in a system. It is an important concept in thermodynamics and helps us understand the direction of energy flow and the efficiency of processes. Entropy also plays a role in understanding the behavior of chemical reactions and the stability of systems.

2. How did Svante Arrhenius' salt water experiment contribute to our understanding of entropy?

In his experiment, Arrhenius observed that when salt is added to water, the molecules of water become more disordered, leading to an increase in entropy. This helped to support the idea that entropy tends to increase in natural processes, which is known as the second law of thermodynamics.

3. Can entropy be reversed or decreased?

According to the second law of thermodynamics, the overall entropy of a closed system will tend to increase over time. However, it is possible to decrease the entropy of a small part of a system by inputting energy and organizing the molecules. This is how living organisms are able to maintain low entropy and order in their bodies.

4. How is entropy related to the concept of equilibrium?

Entropy is closely related to the concept of equilibrium, which is a state of balance or stability in a system. In a closed system, entropy will tend to increase until it reaches equilibrium, where the system is at its maximum entropy. This is why natural processes tend to move towards equilibrium.

5. How does entropy apply to real-world situations?

Entropy has many practical applications, such as in the design of efficient engines and refrigeration systems. It also helps us understand the behavior of systems in nature, such as weather patterns and the formation of stars. Additionally, the concept of entropy is important in fields like chemistry, biology, and economics.

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