## Calculating Delta G, Delta S, and Delta H

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

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

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

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Mara Lockhart 3J
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### Calculating Delta G, Delta S, and Delta H

For problem 8.101 in the book, I am confused as to what products and reactants are to be used for the standard enthalpies and entropies. Well, now looking at it more, I am just confused over all. Could some one explain how we use the lewis structures and compounds to find the Delta H, Delta S, and Delta G for all three compounds including 2-methylpropene, cis-2-butene, and trans-2-butene.

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### Re: Calculating Delta G, Delta S, and Delta H

You do not need to use Lewis structures to calculate delta G, delta S, and delta H. The three reactions that interconvert each pair of compounds (which part b refers to), are the following:

1) cis-2-butene <--> trans-2-butene
2) cis-2-butene <--> 2-methylpropene
3) trans-2-butene <--> 2-methylpropene

You can use the given standard enthalpy and Gibbs free energy of formation to calculate the delta G and delta H of the reactions.

Mara Lockhart 3J
Posts: 53
Joined: Fri Sep 26, 2014 2:02 pm

### Re: Calculating Delta G, Delta S, and Delta H

Okay! That makes a lot more sense! Thank you

Justin Le 2I
Posts: 142
Joined: Fri Sep 26, 2014 2:02 pm

### Re: Calculating Delta G, Delta S, and Delta H

The Lewis structures would be useful if you were calculating the enthalpy of reaction by using bond enthalpies, but we're not using that method here and it's also more inaccurate.

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