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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: sn1sn2e1e2 on April 19, 2014, 04:08:13 PM

Title: delta G and K
Post by: sn1sn2e1e2 on April 19, 2014, 04:08:13 PM

A large positive value of ΔG° corresponds to which of these?

(A) small positive K
(B) small negative K
(C) large positive K
(D) large negative K

The question gives no further details about enthalpy so you do not know if it's endo or exo.

I chose D thinking that the negative signs cancel out in G=H-TS but the correct one is A!

How do you solve this ambiguous problem?

{MOD Edit} replace KoOl TiTlE with a useful title

Title: Re: QuIcK QuEsTiOn
Post by: Borek on April 19, 2014, 04:41:47 PM

Nothing ambiguous here, there is a well known, simple relationship between ΔG° and K.

Is negative K possible at all?

Title: Re: delta G and K
Post by: sn1sn2e1e2 on April 19, 2014, 05:16:06 PM

Isn't the K asking as in terms of Kelvin..?

Title: Re: delta G and K
Post by: Borek on April 19, 2014, 05:29:18 PM

No, K is not a temperature in Kelvins.

Besides, is it possible to have a negative temperature expressed in Kelvins?

Title: Re: delta G and K
Post by: sn1sn2e1e2 on April 19, 2014, 05:33:34 PM

Oh wow, I was not thinking, absolute zero is the "threshold" smallest (if impossible) temperature.

Thanks Borek!