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#1
07-18-2012
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 529 Threads: 57 Thanked 284 Times in 152 Posts Reputation: 294
NBME 7 Gibbs question

Can someone help me with this question please???

Its Block 4 question 50

I know that if delta G is negative, the reaction is spontaneous and concentration of produckts will be favoured and Keq will be more than 1. and the reaction releases energy

And If delta G is positive, concentration of substrate is favored and Keq will be less than 1. and the reaction consumes energy.

But how the hell do u solve this question??????

thanks
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#2
07-18-2012
 USMLE Forums Addict Steps History: 1+CK+CS Posts: 187 Threads: 28 Thanked 101 Times in 56 Posts Reputation: 111

Here's the explanation.. I hope this helps..

Δ G < 0 Sponatneous- reaction will progress to the right (product formation)
Δ G > 0 nonspontaneous- would need energy to go the right or will no energry for the reaction to progress in the opposite direction i.e. right to left
Δ G˚ = 0 the reaction is free to go in any direction.

Now, let's talk about the question..

C is the same.. So ignore C..

Add up A and D, and B and E and also the Δ G of the two equations..

You'd get A+D <-------> E+B Δ G= -4.7

Favoring spontaneous reaction i.e. to the right..

Hence, the answer to that question is (C) -4.7 Direction 1
 The above post was thanked by: husseinalaa (07-18-2012), numbndumb (07-18-2012), Renaissance (07-18-2012)
#3
07-18-2012
 USMLE Forums Scout Steps History: Not yet Posts: 46 Threads: 6 Thanked 21 Times in 11 Posts Reputation: 31

Quote:
 Originally Posted by numbndumb Can someone help me with this question please??? Its Block 4 question 50 I know that if delta G is negative, the reaction is spontaneous and concentration of produckts will be favoured and Keq will be more than 1. and the reaction releases energy And If delta G is positive, concentration of substrate is favored and Keq will be less than 1. and the reaction consumes energy. But how the hell do u solve this question?????? If anyone knows please help. thanks
hey how come I don't see the question? can you post it again please?
thank u
__________________
An Intellectual is someone who's mind watches itself.

#4
07-18-2012
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 529 Threads: 57 Thanked 284 Times in 152 Posts Reputation: 294

Quote:
 Originally Posted by husseinalaa hey how come I don't see the question? can you post it again please? thank u
Its an NBME question. We are not allowed to post them here. You can check nbme form 7.. block 4 question 50
__________________
I've become so numb
 The above post was thanked by: husseinalaa (07-19-2012)
#5
07-19-2012
 USMLE Forums Scout Steps History: Not yet Posts: 46 Threads: 6 Thanked 21 Times in 11 Posts Reputation: 31

Quote:
 Originally Posted by numbndumb Its an NBME question. We are not allowed to post them here. You can check nbme form 7.. block 4 question 50
__________________
An Intellectual is someone who's mind watches itself.

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