## Units for Gibbs

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

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

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

305421980
Posts: 101
Joined: Sat Sep 07, 2019 12:16 am

### Units for Gibbs

Why is it that sometimes delta G is in kj and other times it is in kj/mole when each time you have to incorporate moles?

305421980
Posts: 101
Joined: Sat Sep 07, 2019 12:16 am

### Re: Units for Gibbs

For example in calculating K in problem 5G21 the units used are only in KJ for the values of delta G

Alice Chang 2H
Posts: 101
Joined: Fri Aug 30, 2019 12:18 am

### Re: Units for Gibbs

They're actually assuming that you know the units for ∆G to be kJ/mol. A lot of times, the textbook omits the "/mol" part because it is assumed to be included.

Eva Zhao 4I
Posts: 101
Joined: Sun Sep 29, 2019 12:16 am

### Re: Units for Gibbs

As a general rule, anything with the ∆_r is per mole. Regarding ∆G (according to the reply of a similar question), free energy can have the units of kJ or kJ/mol depending on whether the question refers to the molar free energy of a substance or the free energy of a specific amount of the substance. Try to write out all your units and make sure they cancel properly to get the right units.