Lecture Example/delta G naught at a different temp

[BrittneyMyint1D]

Hi! In lecture, Dr. Lavelle used the deltaGnaught = (the sum of the deltaG products) - (the sum of the deltaG reactants) equation to solve for deltaG naught of the reaction. However, I noticed that the reaction takes place at T = 1943 K, and I recalled from some previous homework problems that we weren't able to use this equation at temperatures other than 298 K. Instead, we had to calculate delta H naught and delta S naught and then use the deltaG naught = (deltaH naught) - T*(deltaS naught) equation to solve for deltaG naught.

Are we able to use deltaGnaught = (the sum of the deltaG products) - (the sum of the deltaG reactants) at temperatures other than 298 K? Thanks in advance!

[Akash J 1J]

Yes. This is because the equation for
delta G0 = RTlnK
accounts for temperatures that are not 298 K. Hence, delta G0 can be found at different temperatures. As for delta G0 = products - reactants, the Gibbs free energy values for the products and reactants must be corresponding to the same temperature as the reaction.

[BrittneyMyint1D]

Yes. This is because the equation for
delta G0 = RTlnK
accounts for temperatures that are not 298 K. Hence, delta G0 can be found at different temperatures. As for delta G0 = products - reactants, the Gibbs free energy values for the products and reactants must be corresponding to the same temperature as the reaction.

That makes sense, thank you so much!

[905934944]

but if delta G0 can be culauated at different temperatures why is it defined as the standard change in gibbs free energy if it doesn't have to be at 298K?