Reversible and Isothermal

isochoric/isometric:
isothermal:
isobaric:

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Rachel Yu 1G
Posts: 113
Joined: Fri Aug 09, 2019 12:15 am

Reversible and Isothermal

Postby Rachel Yu 1G » Mon Feb 10, 2020 10:24 am

I am pretty sure isothermal reactions are not always reversible. However, can we assume that reversible reactions are always isothermal? Thanks!

Jessica Li 4F
Posts: 115
Joined: Fri Aug 09, 2019 12:16 am

Re: Reversible and Isothermal

Postby Jessica Li 4F » Mon Feb 10, 2020 11:43 am

I think you can assume that reversible equations are isothermal. Think of a phase change, which is at equilibrium and isothermal.

Emily Chirila 2E
Posts: 112
Joined: Sat Jul 20, 2019 12:16 am

Re: Reversible and Isothermal

Postby Emily Chirila 2E » Mon Feb 10, 2020 11:44 am

I think that generally, irreversible expansion occurs in real life situations, so we assume temp is changing, unless it is a phase change (which are isothermal). Reversible expansion calculations are hypothetical maximums and temp is always kept constant, which we can see in the equation w=-nrTln(v2/v1) where T does not have a delta in front of it.

sarahsalama2E
Posts: 164
Joined: Fri Aug 30, 2019 12:16 am

Re: Reversible and Isothermal

Postby sarahsalama2E » Mon Feb 10, 2020 2:01 pm

also, for an isothermal reaction, is delta u equal to 0?

Emily Chirila 2E
Posts: 112
Joined: Sat Jul 20, 2019 12:16 am

Re: Reversible and Isothermal

Postby Emily Chirila 2E » Tue Feb 11, 2020 11:32 am

sarahsalama2E wrote:also, for an isothermal reaction, is delta u equal to 0?


Yes, internal energy depends on temperature so for isothermal expansion deltaU=0 and thus:
deltaU=q+w ------> 0=q+w ------> q=-w


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