Why is Delta S purely dependent on gases?

  • Thread starter Thread starter patrickbotros
  • Start date Start date
  • Tags Tags
    Delta Gases
AI Thread Summary
The discussion centers on the relationship between the number of moles of gas and entropy changes. It emphasizes that an increase in the number of moles of gas typically leads to an increase in entropy (ΔS>0), as stated by the teacher. However, the example provided raises questions about this principle, particularly when considering reactions that involve both gas and liquid phases, which can complicate the interpretation of moles and their impact on entropy. The conversation highlights the importance of understanding the processes that lead to changes in the number of moles and clarifies that the principle of entropy as an extensive property is crucial in these discussions. Overall, while the increase in moles of gas generally correlates with increased entropy, specific reactions may require deeper analysis to fully understand the entropy changes involved.
patrickbotros
Messages
34
Reaction score
1
My teacher constantly stresses that 10 moles of a gas going to 11 moles of a gas will ALWAYS cause an increase in entropy (ΔS>0). But why? For example (I know that O2 shouldn't technically be a liquid, but just as an example):
2H2O(g)⇔H2O(g)+(3/2)O2(l)+2H2
It seems iffy to me. We go from 2mol(g)↔1mol(g), BUT we also have 2moles⇔(7/2)moles. Is the moles of gas rule just a "it usually works" kind of rule, or is it a tried-and-true physics fact?
Thanks so much! :smile:
 
Chemistry news on Phys.org
patrickbotros said:
10 moles of a gas going to 11 moles of a gas

10 moles of a gas don't change into 11 moles of a gas, that's mass conservation at wok. Apparently you think about some process in which number of moles of gas changes - but what process it is, and why does the number of moles of gas change? What are other things involved?

Or perhaps you just misunderstand the idea that entropy is an extensive property?
 

Thread 'Solubility of MgSO47H2O in water'

It seems like a simple enough question: what is the solubility of epsom salt in water at 20°C? A graph or table showing how it varies with temperature would be a bonus. But upon searching the internet I have been unable to determine this with confidence. Wikipedia gives the value of 113g/100ml. But other sources disagree and I can't find a definitive source for the information. I even asked chatgpt but it couldn't be sure either. I thought, naively, that this would be easy to look up without...
View full post »

Thread 'Why does having 8 valence electrons make an element inert?'

I was introduced to the Octet Rule recently and make me wonder, why does 8 valence electrons or a full p orbital always make an element inert? What is so special with a full p orbital? Like take Calcium for an example, its outer orbital is filled but its only the s orbital thats filled so its still reactive not so much as the Alkaline metals but still pretty reactive. Can someone explain it to me? Thanks!!
View full post »

Similar threads

I Energy balance over a methanol reformer
Replies
4
Views
2K
How Do You Calculate the Enthalpy Change for Methane Combustion?
Replies
2
Views
19K
Thermodynamics: Enthelpy of Sucrose
Replies
1
Views
20K
Fortran Why Am I Getting an 'Out of Range in G Table' Error in FORTRAN?
Replies
1
Views
3K
Are Nonpolar Liquids Dangerous and What Are Their Harmful Effects?
Replies
17
Views
5K
Textbooks on Condensed Matter Physics
Replies
19
Views
18K

Hot Threads

Recent Insights

Back
Top