Equilibrium & Solubility constants: What does the following statement mean?

[AlwaysLucky]

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In TPRH General Chem section, one of the answer explanation states the following:

"Equilibrium & solubility constants of any substance are only functions of temperature, NOT pressure, concentration, or presence of catalyst"

Could anyone explain what this means using an easy example? I'm confused because Keq is equal to [products] / [reactants], so it certainly depends on concentration, right? or is my logic flawed?

Totally random: If the real AAMC is anything like these gen chem passages, I might as well give up now ... these questions are ridiculous~ lol

 

[shaboobly]

it means the value of K will always be the same at a specific temperature and will not be changed by changing the concentrations or any of the other listed variables. regardless of the concentrations you start with, the ratio will always end up being the same.

 

[sciencebooks]

it means the value of K will always be the same at a specific temperature and will not be changed by changing the concentrations or any of the other listed variables. regardless of the concentrations you start with, the ratio will always end up being the same.

Because basically if you changed any of the other things, it will just restore itself to equilibrium via Le Chatelier's principle, right?

 

[AlwaysLucky]

Uggh I didn't think about Le Chatelier's principle; so basically, even if we change the [ ] in whatever fashion, we'll always end up with the same Keq at a specified temperaure ...

 

[shaboobly]

when you change something that is eq, you start to use Q and then Q is shifted to equal K

 

[argama]

I interpret that as ONLY temperature can change the Keq and nothing else due to le Chatelier's Principle.

 

[sciencebooks]

I interpret that as ONLY temperature can change the Keq and nothing else due to le Chatelier's Principle.

I operate on this basic thought too. Is there anything more we should know? Like does an INCREASE in temperature change Keq a certain way (like up or down) or is this not something we could possibly know without experimental data?

 

[shaboobly]

I operate on this basic thought too. Is there anything more we should know? Like does an INCREASE in temperature change Keq a certain way (like up or down) or is this not something we could possibly know without experimental data?

if you know whether the reaction is endo or exothermic, you can predict how increasing the temp will change equilibrium based off of le chatliers principle.
exothermic: increase heat (heat is produced in the reaction thus adding heat, increasing temp, will inhibit the formation of more product and the value of K will decrease)
endothermic: increase heat (heat is required for the reaction to run, and increasing temp will increase the "reactants" and create more product thus increasing K.

 

[sciencebooks]

if you know whether the reaction is endo or exothermic, you can predict how increasing the temp will change equilibrium based off of le chatliers principle.
exothermic: increase heat (heat is produced in the reaction thus adding heat, increasing temp, will inhibit the formation of more product and the value of K will decrease)
endothermic: increase heat (heat is required for the reaction to run, and increasing temp will increase the "reactants" and create more product thus increasing K.

Lol, nevermind, that's exactly what you said. I just misread. But yep, got it, thanks. I kind of think of this as Le Chateliers too; in exothermic, heat's a "product" and in endothermic, heat's a "reactant" but the shifts in this case, actually change the Keq.