How deltaG affects product/reactant formation

[Isabelle Hales 1J]

In last Friday’s lecture, Lavelle mentioned that when K > 1, deltaG under standard conditions is negative. He said that there are more products that reactants which will cause product formation to be favored. I am a bit confused by this. I thought that if there are more products than reactants, the formation of reactants would be favored. Can someone help me understand this?

[AnjikaFriedman-Jha2D]

He might be saying that when there are more products than reactants the delta G of the reverse reaction is negative and thus that is what is spontaneous

[Sami Siddiqui 1J]

In the long run, to have a negative delta G value means that K (the equilibrium constant) will be greater than 1, meaning that the equilibrium concentrations will favor the products over the reactants as the reaction approaches equilibrium. This is given by the fact that, on a conceptual level, K is essentially [P]/[R] (while factoring in all the stoichiometric coefficients as exponents for each substance). To have a positive delta G value means that K will be less than 1, meaning that vice versa will be true. In the context of chemical equilibrium, if we took a system that was already at equilibrium and then added more product to it, then the reactants would be favored according to Le Chatelier's principle.

[Aydin Karatas 1F]

If we look at the equation for at standard condition, we get . For to be negative, thus meaning the reaction favors the products, we need to produce a positive number. When K > 1, < 0. When 0 < K < 1, > 0. Since R is a positive constant and T is given in Kelvin, we can see that the favorability of a reaction is depended on in this expression.

[Victor Qiu 1C]

It is not true that if there are more products than reactants, the formation of reactants would be favored. You can just think of an example of dissociation of a strong acid.
HCl(aq) + H₂O(l) → H₃O⁺(aq) + Cl^-(aq)
The products are favored even when there are more products than reactants.

[Grace_Remphrey_2J]

I was also confused about this and these explanations were super helpful. Thank you!!

[SavannahScriven_1F]

When K is > 1, the equilibrium lies to the right (i.e. at equilibrium, there is a higher concentration of products than reactants). Delta G would be negative because the forward reaction is favored (product form is more stable than reactant form, so rxn is spontaneous).