CHEMISTRY COMMUNITY

How does delta G tell us which way a reaction will shift?

delta G has a relationship with the equilibrium constant through the equation delta G= -RTln(K. This means that with delta G we will be able to make calculations and therefore determine which way the equilibrium leans by analyzing the eqwuilibrium constant relative to Q

When delta G is negative, the reaction is spontaneous and will shift towards the products. When it is positive, the reverse reaction is spontaneous and will shift towards the reactants.

If delta G is negative, that means that the forward reaction is favored and that the products will be favored because K>1. (You could then say that the reaction shifts to the right.)

If the delta G is positive, that means that the forward reaction is not favored (the backwards reaction is favored) and that the reactants will be favored because K<1. (You could then say that the reaction shifts to the left.)

Altamash Mahsud 1I wrote:If delta G is negative, that means that the forward reaction is favored and that the products will be favored because K>1. (You could then say that the reaction shifts to the right.)

If the delta G is positive, that means that the forward reaction is not favored (the backwards reaction is favored) and that the reactants will be favored because K<1. (You could then say that the reaction shifts to the left.)

What would it mean if delta G was zero?

When G=0, the reaction is at equilibrium.

When deltaG=0, the system is at equilibrium (the forward and reverse reactions occur at the same rate)
When deltaG is negative, the forward reaction is spontaneous
When deltaG is positive, the reverse reaction is spontaneous

When delta G is negative it becomes spontaneous and the reaction will favor the products if delta G is positive the reaction will favor the reactants

You can also alter the concentration of products to reactants in order to change the G value.
if you increase the amount of product, the lnK part of the expression will become greater, making the G value more negative. Delta G will be negative, thus the reaction will be more spontaneous.
If you decrease the amount of product, the lnK part of the expression will become smaller, making the G value more positive. Delta G will be positive, thus the reaction will be less spontaneous.

To add on, when ∆G=0 the system is at equilibrium. When ∆G is negative, the forward reaction is spontaneous. When ∆G is positive, the reverse reaction is spontaneous
The sign of ∆G depends on the enthalpy, entropy, and temperature. The table below shows you the relationship between these variables and the sign of ∆G.