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Reversible and Isothermal

Posted: Mon Feb 10, 2020 10:24 am
by Rachel Yu 1G
I am pretty sure isothermal reactions are not always reversible. However, can we assume that reversible reactions are always isothermal? Thanks!

Re: Reversible and Isothermal

Posted: Mon Feb 10, 2020 11:43 am
by Jessica Li 4F
I think you can assume that reversible equations are isothermal. Think of a phase change, which is at equilibrium and isothermal.

Re: Reversible and Isothermal

Posted: Mon Feb 10, 2020 11:44 am
by Emily Chirila 2E
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.

Re: Reversible and Isothermal

Posted: Mon Feb 10, 2020 2:01 pm
by sarahsalama2E
also, for an isothermal reaction, is delta u equal to 0?

Re: Reversible and Isothermal

Posted: Tue Feb 11, 2020 11:32 am
by Emily Chirila 2E
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