Understanding Entropy: A Comprehensive Explanation for Beginners

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Discussion Overview

The discussion centers around the concept of entropy, its implications in spontaneous processes, and related thermodynamic principles such as Gibbs free energy. Participants express confusion about the nature of entropy, its increase in spontaneous occurrences, and the relationship between temperature changes and entropy. The scope includes conceptual clarifications and technical explanations related to thermodynamics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on how entropy can constantly increase from spontaneous occurrences, questioning the implications of entering a vacuum.
  • Another participant discusses the relationship between heating a gas and its entropy, asking if decreasing the temperature results in a proportional decrease in entropy.
  • There is a query about the definition of "ordered" and "disordered" states, suggesting that a standard is needed to determine disorder.
  • A participant mentions that adding heat increases entropy but argues that this process does not relate to spontaneity.
  • One participant references Gibbs free energy, questioning its definition and the assertion that it always increases, while noting that it can be negative.
  • Another participant explains that for spontaneous reactions at constant temperature and pressure, the change in Gibbs free energy should be negative, linking it to the Clausius inequality.

Areas of Agreement / Disagreement

Participants express various viewpoints on entropy and Gibbs free energy, with no consensus reached on the definitions or implications of these concepts. Multiple competing views remain regarding the nature of disorder and the relationship between temperature changes and entropy.

Contextual Notes

Participants reference specific thermodynamic principles and equations, but the discussion includes unresolved questions about definitions and the implications of entropy changes in different scenarios.

Who May Find This Useful

This discussion may be useful for beginners in thermodynamics, students seeking clarification on entropy and Gibbs free energy, and individuals interested in the conceptual underpinnings of spontaneous processes in physics and chemistry.

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Can anyone please explain entropy!
its so confusing. i looked it up and i don't get it.
How can entropy constantly be increaseing from every spontaneous occurrence?
for example, if here on earth, you g ointo a vacume, wouldn't you freeze? because it was absolute zero is it was a vacume...
thanks
 
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If you take a can filled with air, and heat it up 10 degrees more than it was 9lets say it started at 25 degrees celsius, the entropy is increased right...because the process was spontaneous.

now what if you decrease the temperatue 10 degree, then the entropy is decreased right? is the entorpy decreased the same amount it was increased when it was heated up?



Why is the reaction considered "spontaneou" when you were ading heat to it...?


thanks
 
Maybe whast confusing me is what is considered to be more disordered.

In order to determine if something is disordered, then there has to be a standard of what is considered ordered...

so what is ordered?
 
How can entropy constantly be increaseing from every spontaneous occurrence?
for example, if here on earth, you g ointo a vacume, wouldn't you freeze? because it was absolute zero is it was a vacume...

absolute zero pertains to temperature, temperature is related to the kinetic energy; in this sense how would you freeze in the vacuum void of particulate matter (the idea is a bit absurd to begin with).

If you take a can filled with air, and heat it up 10 degrees more than it was 9lets say it started at 25 degrees celsius, the entropy is increased right...because the process was spontaneous.

now what if you decrease the temperatue 10 degree, then the entropy is decreased right? is the entorpy decreased the same amount it was increased when it was heated up?

Why is the reaction considered "spontaneou" when you were ading heat to it...?

yes you increase the entropy by adding heat energy to the system of such gases, this process in and of itself has nothing to do with spontaneity.

For your second question, and for a simplistic case, yes. [tex]( \frac{du}{dT} )_{p,n} = -Sm[/tex] that is the slope of molar free energy with respect to temperature for such a first order transition is equivalent to the negative of the molar entropy. With a cyclic process, you'll return to the same state entropy under particular conditions. Try finding a entropy v.s. temperature plot through google.

You can try out a calculation, using dq(rev)=TdS, and knowing the dq=Cv(dT) at constant volume (relatively constant heat capacity over a small temperature range). Find out how much heat is required to heat the sample 10 degrees from a certain temperature and then find the entropy change, then the same for the cooling process.

Maybe whast confusing me is what is considered to be more disordered.

In order to determine if something is disordered, then there has to be a standard of what is considered ordered...

so what is ordered?
asyou mentioned, at lower temperatures, certain matter is more ordered, try researching up on the Nernst heat theorem. There are many perspectives of entropy, for one it has to do with the number of energy states being considered respectively.
 
ok thanks.

You mentioned free energy. I looked through my textbook, and it defines it as, G= H- TS, but never tells what gree energy (gibbs free energy) is, or what its good for.

i was looking online, and it said that gibbs free energy ALWAYS increases, but can't gibbs energy be negative, and therefor decrease?

can you help me with that please.

thanks
 
ok thanks.

You mentioned free energy. I looked through my textbook, and it defines it as, G= H- TS, but never tells what gree energy (gibbs free energy) is, or what its good for.

i was looking online, and it said that gibbs free energy ALWAYS increases, but can't gibbs energy be negative, and therefor decrease?

can you help me with that please.

thanks
For a spontaneous reaction at constant temperature and pressure the change in Gibb's energy should be negative in value. Gibb's energy is derived from the clausius inequality and the criterion for spontaneity (dS+dSsurr> or equal to 0). One of the reasons it is useful is that it can be associated with the maximul non-expansion work for a system such as an electrochemical cell.
 

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