Delta G 0 standard conditions

[recyrb]

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I was wondering about delta G knot at equilibrium

under standard conditions there is 1 molar of both products and reactants so at equilibrium Delta G = 0 so you can relate Delta G knot to Keq

Delta Gknot= -RTLnKeq

if delta Gknot is ( - ) than the reaction is spontaneous so Keq is a positive number > 1

Keq > 1 in my mind means there are more products than reactants
prod/rxts greater than one

so how is Gknot related to Keq if when spontaneous there are more products than reactants meaning that the concentrations are not 1 molar: 1 molar?? meaning this is not at standard conditions, what am I missing?

thanks

 

[recyrb]

bump

 

[rizzler]

I was wondering about delta G knot at equilibrium

under standard conditions there is 1 molar of both products and reactants so at equilibrium Delta G = 0 so you can relate Delta G knot to Keq

Delta Gknot= -RTLnKeq

if delta Gknot is ( - ) than the reaction is spontaneous so Keq is a positive number > 1

Keq > 1 in my mind means there are more products than reactants
prod/rxts greater than one

so how is Gknot related to Keq if when spontaneous there are more products than reactants meaning that the concentrations are not 1 molar: 1 molar?? meaning this is not at standard conditions, what am I missing?

thanks

So if the concentrations of products and reactants is 1:1 you are at equilibrium where you get the equation Delta Gknot= -RTLnKeq

I'm guessing you're asking why is Keq positive when the concentrations are not 1 to 1? if your products and reactants are not 1 to 1, you are not under standard conditions. you use the equation Delta G = Delta Gknot + RTLnQ (this is how Delta Gknot= -RTLnKeq is derived... at equilibrium delta G = 0)


lets just try to understand the relationship between Delta Gknot= -RTLnKeq

if we have Delta G(knot) < 0 the reaction is spontaneous under standard conditions. this says nothing about being under non-standard conditions, the reaction may or may not be spontaneous (you would have to calculate it)
in this case you have 1:1 ratio of reactants to products.
you see the reaction proceeds from reactants --> products (left to right) meaning when you reach equilibrium you end up with more products than reactants. so your ratio of products to reactants should be greater than one making Keq > 1.



if we have delta G(knot) > 0 you still have a ratio of 1 :1 products to reactants but the reaction is NOT spontaneous.
we can state that reactants --> products is not spontaneous but if it is not spontaneous left to right it must be spontaneous right to left or reactants <-- products making your ratio less than one (more reactants than products) making Keq < 1.

if delta G (not) = 0 then your keq = 1.

hope that helps.

 

[recyrb]

yes i appreciate it... i alway confuse these things after 8 hour days lol thanks man

 

[rizzler]

yes i appreciate it... i alway confuse these things after 8 hour days lol thanks man

no problem... when I saw this question I blanked also, I had to go through my review notes and i face palmed myself and was like omg this is easy, how do i keep forgetting this stuff. I'm doing those 8 hour days also =.="

good luck studying.

 

[wall1two]

Delta g for the win