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Gibbs free energy Watch

1. To work out delta G im first carrying out a reaction to determine enthalpy change via Q=mcdeltaT.
in the gibbs free energy equation is the temperature in kelvin equal to whatever my temperature change is in the mcdeltaT. And say if the temp change was -20 it would be 253K for the gibbs equation?
2. (Original post by User101010)
To work out delta G im first carrying out a reaction to determine enthalpy change via Q=mcdeltaT.
in the gibbs free energy equation is the temperature in kelvin equal to whatever my temperature change is in the mcdeltaT. And say if the temp change was -20 it would be 253K for the gibbs equation?
Temperature change is a difference and so the units do not matter (as 1 degree celsius change = 1 Kelvin change)
3. (Original post by charco)
Temperature change is a difference and so the units do not matter (as 1 degree celsius change = 1 Kelvin change)
So do I use the final temperature say if went from 35 to 25 is use 298k
4. (Original post by User101010)
So do I use the final temperature say if went from 35 to 25 is use 298k
Q=mcΔT

You are using the temperature change.It does not matter whether you record the values in Celsius or Kelvin.
5. If the temperature went from 10 to 25 degrees what value would I use for T in the Gibbs free energy equation
6. If temp. goes from 35 oC to 25 oC, that's a change of 35-25=10 oC.

If temp. goes from 308 K to 298 K, that's a change of 308-298=10 K.

They're the same thing.
7. I know they are the same but I am asking do I use the change for T in gibbs equation or what the final temp is
8. (Original post by User101010)
I know they are the same but I am asking do I use the change for T in gibbs equation or what the final temp is
You are clearly getting mixed up with two different issues.

You have to work out the enthalpy change of a reaction. Do it using E=mcΔT

Then you use your value for the enthalpy change, which does not vary with temperature (to a close approximation) with entropy values at a specific temperature (usually 298K) to find Gibbs free energy for that specified temperature.

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Updated: January 8, 2015
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