Measuring delta G

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Simrina Desar Dis 1H
Posts: 49
Joined: Fri Sep 29, 2017 7:04 am

Measuring delta G

Postby Simrina Desar Dis 1H » Sun Feb 04, 2018 9:53 pm

Is there any way to measure delta G? Or is the only way to calculate it using enthalpy and entropy?

Scott Chin_1E
Posts: 55
Joined: Sat Jul 22, 2017 3:00 am

Re: Measuring delta G

Postby Scott Chin_1E » Sun Feb 04, 2018 9:56 pm

No, there is no machine which we can use to measure DeltaG. The only way to get a value for deltaG is by calculating for it using

deltaG = deltaH - T(deltaS)

Jessica Patzlaff 1A
Posts: 28
Joined: Fri Sep 29, 2017 7:05 am

Re: Measuring delta G

Postby Jessica Patzlaff 1A » Sun Feb 04, 2018 9:59 pm

In problems dealing with multiple reactions, there are values in the appendix giving the standard Gibbs free energy for various reactions, which will be used like with standard enthalpy calculations.

Ethan Vuong 3G
Posts: 51
Joined: Fri Sep 29, 2017 7:07 am

Re: Measuring delta G

Postby Ethan Vuong 3G » Sun Feb 04, 2018 10:28 pm

Calculate deltaG by using standard enthalpy of formation and standard entropy values of R and P. So delta G =deltaH-Tdelta S.

Rachel Formaker 1E
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Re: Measuring delta G

Postby Rachel Formaker 1E » Sun Feb 04, 2018 10:33 pm

Since we cannot measure ΔG directly, we use equations with values that we can measure to calculate ΔG.

We can measure equilibrium concentrations to calculate the equilibrium constant K, so we can calculate ΔG using K from measured concentrations:
ΔGo = -RTlnK

If the system is not at equilibrium, we use:
ΔG = ΔGo + RTlnQ

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