## signs of G with different values of K

$\Delta G^{\circ}= \Delta H^{\circ} - T \Delta S^{\circ}$

$\Delta G^{\circ}= -RT\ln K$

$\Delta G^{\circ}= \sum \Delta G_{f}^{\circ}(products) - \sum \Delta G_{f}^{\circ}(reactants)$

Clarice Chui 2C
Posts: 101
Joined: Fri Aug 30, 2019 12:16 am

### signs of G with different values of K

Why is delta G positive when K is less than one and vice versa?

peteryim
Posts: 54
Joined: Sat Sep 07, 2019 12:17 am

### Re: signs of G with different values of K

For the delta G equation at equilibrium, you take the natural log of K. If K is less than 1 but greater than 0 (so a fraction) then the value of the natural log will be a negative number. That's why it will be negative.

Jonathan Gong 2H
Posts: 105
Joined: Sat Jul 20, 2019 12:16 am

### Re: signs of G with different values of K

delta G is positive when K is less than 1 because the equation is dG = -RTlnK. When K is less than one, lnK is negative, which cancels out the negative sign and makes delta G positive. Vice versa, when K is greater than 1, lnK is positive, which makes delta G negative.

Sofia Barker 2C
Posts: 101
Joined: Wed Sep 18, 2019 12:21 am

### Re: signs of G with different values of K

Delta G is positive when K is less than one because the ln of a fraction is a negative number. Since there is a negative sign in the equation delta G = -RT ln K, the two negatives cancel and the overall value is positive.