Organic chem HELP!

[dfymarine]

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OKAY!

here is the conceptual Q that is likely to be on the DAT:

According to the le Chatelier's principle, the direction in which a reaction at equilibrium will proceed can only be influenced by a change in :

A) Pressure

B) Temperature

C) Volume

D) Concentration

E) Catalyst

F) A- D

E) all of above
from doing the destroyer problems, I learned that an equilibrium can only be changed by temperature only, so I chose B


maybe I am thinking too much, what do you guys think of it

thanks!

 

[NumbaOneStunna]

I think it's A-D, I could be wrong though. It's def not A-E or E because catalysts only affect rates and not equilibrium. What you said about temperature being the only factor able to change the location of equilibrium is correct, but the question says "the direction in which a reaction at equilibrium will proceed can only be influenced". My understanding is that changes in temp will change K (the equilb. constant) but not Q ( the rxn quotient), and that changes in the other choices excluding catalysts change Q. The result in a change in Q from K is that the rxn is either "shifted right" or "left" at equilibrium which seems to fit with what the question is asking.

Hopefully that made sense, just woke up and thanks for the question- I realized I'm a lil weak in this area.

 

[dfymarine]

I think it's A-D, I could be wrong though. It's def not A-E or E because catalysts only affect rates and not equilibrium. What you said about temperature being the only factor able to change the location of equilibrium is correct, but the question says "the direction in which a reaction at equilibrium will proceed can only be influenced". My understanding is that changes in temp will change K (the equilb. constant) but not Q ( the rxn quotient), and that changes in the other choices excluding catalysts change Q. The result in a change in Q from K is that the rxn is either "shifted right" or "left" at equilibrium which seems to fit with what the question is asking.

Hopefully that made sense, just woke up and thanks for the question- I realized I'm a lil weak in this area.

I totally understand your interpretation, and it clears up a lot for me, thanks!

However, at equilibrium , according to my understanding that the Q should be equal to K, and hence Q would not be applied in this case?

 

[NumbaOneStunna]

My understanding of the question was it's initially at equilibrium (Q=K) but then a stimulus ( change in pressure, volume etc) is provided and this changes Q or K. I should say that I think this question is worded poorly, but it could be just me.

 

[alanan84]

The only thing that can change the equilibrium constant is temp. However, once you apply a change, as "Stunna" said, K will change to Q.

Remember that Le Chatelier's principle always applies to a system that is already at equilibrium. So if you change A-D, the reaction will shift according to Le Chatelier's principle. The only way you can change a Keq for a given reaction however is by changing the temp.

 

[nze82]

okay!

Here is the conceptual q that is likely to be on the dat:

According to the le chatelier's principle, the direction in which a reaction at equilibrium will proceed can only be influenced by a change in :

A) pressure>>>this can change the direction. Pv = nrt. The higher p, the higher the number of moles. To compensate for the increased number of moles, the reaction will move in the direction with lower number of moles of gas.

b) temperature>>>this can change the direction. In endothermic/exothermic reactions heat can serve as one of the reactants or products respectively. So, adding heat or removing heat is just like adding to the products side or the reactant side, and the reaction must shift in one direction or another to compensate for this change.

c) volume>>>this can change direction. Pv = nrt. Change in v affects p, and as we saw in a, change in p can change the direction in which the reaction proceeds.

d) concentration>>>this can change. Similar explanation as b.

e) catalyst>>>this has no effect on the direction. It simply speeds up the reaction in the intial direction.

f) a- d

e) all of above
from doing the destroyer problems, i learned that an equilibrium can only be changed by temperature only, so i chose b


maybe i am thinking too much, what do you guys think of it

thanks!