TBR Ochem Ch 1; Pass 1 #3

[MAnne]

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I've tried reading the explanation but I still can't comprehend the methodology.

Not understanding how the answer is D). 345 for this:

What is the value of Keq-1.4 for the conversion of trans-1,4-dimethylcyclohexane from its diaxial conformation to its diequatorial conformation.

Thanks,
~M

 

[milski]

Keq=[conformation A]/[conformation B]

There must be some additional information about how much you have in each conformation at equilibrium. But there is not much more that can be said without seeing the rest of the problem/explanation.

 

[MedPR]

If I remember correctly, this question is most easily/quickly answered by process of elimination. You know it's greater than 1, since the product is way more stable than the reactant. I think only 2 of the answers were greater than 1? You also know the Keq is greater than the Keq of the comparable reaction in the passage, and I think that Keq was something like 4.3?

345 was the only answer greater than 4.3.

 

[MAnne]

If I remember correctly, this question is most easily/quickly answered by process of elimination. You know it's greater than 1, since the product is way more stable than the reactant. I think only 2 of the answers were greater than 1? You also know the Keq is greater than the Keq of the comparable reaction in the passage, and I think that Keq was something like 4.3?

345 was the only answer greater than 4.3.

Yes, you are correct. The choices are A. 0.0029 B. 2.16 C. 4.31

I wanted to know how to derive at the question without having to do process of elimination. Maybe another example so I can understand the concept, if possible or needed, for that matter.

Thank you for replying.

~M

 

[MedPR]

Keq=[conformation A]/[conformation B]

There must be some additional information about how much you have in each conformation at equilibrium. But there is not much more that can be said without seeing the rest of the problem/explanation.

Yes, you are correct. The choices are A. 0.0029 B. 2.16 C. 4.31

I wanted to know how to derive at the question without having to do process of elimination. Maybe another example so I can understand the concept, if possible or needed, for that matter.

Thank you for replying.

~M

What milski said is correct. Though, if I recall correctly, they didn't give you any concentration values. The answer must come from background knowledge of:

1. Diequatorial is more stable than diaxial
2. Keq = [products]/[reactants]