S = 0

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Drew Myers 4G
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S = 0

Postby Drew Myers 4G » Sun Feb 16, 2020 8:16 pm

When does entropy equal zero?

JonathanS 1H
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Re: S = 0

Postby JonathanS 1H » Sun Feb 16, 2020 8:20 pm

Entropy total is equal to 0 when there is a reversible reaction since the reaction is 'at equilibrium' throughout the whole time. Entropy of the surroundings is equal to 0 with an expansion against a vaccum.

805383532
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Re: S = 0

Postby 805383532 » Sun Feb 16, 2020 8:21 pm

Entropy is 0 in an isothermal reversible system.

rabiasumar2E
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Re: S = 0

Postby rabiasumar2E » Sun Feb 16, 2020 8:26 pm

It's zero in an isothermal reversible reaction.

Jessica Katzman 4F
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Joined: Mon Jun 17, 2019 7:24 am

Re: S = 0

Postby Jessica Katzman 4F » Sun Feb 16, 2020 8:56 pm

When your system is isothermal and your reaction is reversible, s = 0 because the reaction is considered at equilibrium throughout.

Shivam Rana 1D
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Re: S = 0

Postby Shivam Rana 1D » Sun Feb 16, 2020 9:07 pm

Entropy can also equal zero at absolute zero when the molecules only have one orientable state (no residual entropy).

Nick Lewis 4F
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Joined: Wed Sep 18, 2019 12:18 am

Re: S = 0

Postby Nick Lewis 4F » Sun Feb 16, 2020 9:14 pm

Entropy is considered 0 in an isothermal reversible expansion reaction because entropy is a state function and ends in the same final state that it initially starts in.

Shutong Hou_1F
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Re: S = 0

Postby Shutong Hou_1F » Sun Feb 16, 2020 9:16 pm

S just means entropy, rather than change in entropy that should be denoted as ΔS. Entropy is almost never 0 (the entropies of all perfect crystals approach zero as the absolute temperature approaches zero; "perfect crystal" refers to a substance in which all the atoms are in a perfectly orderly array.), because even at absolute 0 where all molecular motion has ceased, positional (residual) entropy, present because of different microstates, still exists.

VioletKo3F
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Re: S = 0

Postby VioletKo3F » Sun Feb 16, 2020 9:46 pm

S, or entropy, is zero in an isothermal reversible system since it it always at equilibrium.

Nathan Rothschild_2D
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Re: S = 0

Postby Nathan Rothschild_2D » Sun Feb 16, 2020 9:47 pm

An example would be a perfect crystal like diamond at absolute zero. However absolute zero is impossible to reach at the moment and can only be reached theoretically.

Ivan Tadeja 1G
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Re: S = 0

Postby Ivan Tadeja 1G » Sun Feb 16, 2020 10:06 pm

Shutong Hou_1F wrote:S just means entropy, rather than change in entropy that should be denoted as ΔS. Entropy is almost never 0 (the entropies of all perfect crystals approach zero as the absolute temperature approaches zero; "perfect crystal" refers to a substance in which all the atoms are in a perfectly orderly array.), because even at absolute 0 where all molecular motion has ceased, positional (residual) entropy, present because of different microstates, still exists.


What would be the meaning/differences of positive/negative entropies?

Rhea Shah 2F
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Joined: Thu Jul 25, 2019 12:17 am

Re: S = 0

Postby Rhea Shah 2F » Sun Feb 16, 2020 10:12 pm

In an isothermal reaction, the change in surrounding entropy is zero because energy is not transferred to the surroundings. In a reversible reaction, the total entropy change is equal to zero because the system is in equilibrium.

Sreyes_1C
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Joined: Fri Sep 28, 2018 12:19 am

Re: S = 0

Postby Sreyes_1C » Sun Feb 23, 2020 11:54 pm

its zero for an isothermal reversible reaction!

Renee Grange 1I
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Re: S = 0

Postby Renee Grange 1I » Mon Feb 24, 2020 12:32 am

Entropy = 0 in an isothermal reversible system

Sanjana K - 2F
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Re: S = 0

Postby Sanjana K - 2F » Mon Feb 24, 2020 12:51 am

Ivan Tadeja 1G wrote:
Shutong Hou_1F wrote:S just means entropy, rather than change in entropy that should be denoted as ΔS. Entropy is almost never 0 (the entropies of all perfect crystals approach zero as the absolute temperature approaches zero; "perfect crystal" refers to a substance in which all the atoms are in a perfectly orderly array.), because even at absolute 0 where all molecular motion has ceased, positional (residual) entropy, present because of different microstates, still exists.


What would be the meaning/differences of positive/negative entropies?


Entropy > 0 means the reaction is favoring an increase in disorder and entropy < 0 means it's favoring order (or less disorder).

Philip
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Joined: Sat Sep 07, 2019 12:16 am

Re: S = 0

Postby Philip » Mon Mar 09, 2020 5:12 pm

The total change in entropy is 0 if the system is isothermal and reversible expansion. The entropy change of the surrounding is 0 if the system is isothermal and irreversible expansion.

William Chan 1D
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Re: S = 0

Postby William Chan 1D » Wed Mar 11, 2020 10:40 pm

Having zero entropy is theoretical. The substance must be in a perfect crystal structure at absolute zero. This would eliminate any positional entropy as well as any entropy from movement.

Mariah
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Re: S = 0

Postby Mariah » Thu Mar 12, 2020 9:39 am

rabiasumar2E wrote:It's zero in an isothermal reversible reaction.


Can you explain how we know whether or not it is isothermal?

Anuradha S 1F
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Re: S = 0

Postby Anuradha S 1F » Sat Mar 14, 2020 8:20 pm

Mariah wrote:
rabiasumar2E wrote:It's zero in an isothermal reversible reaction.


Can you explain how we know whether or not it is isothermal?


The problem usually say whether or not a reaction is isothermal


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