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### Understand equation

Posted: **Sun Feb 11, 2018 4:08 pm**

by **Mike Vinci 2B**

For the Standard Reaction entropies, the equation includes the sum of the products with n moles subtracted by the sum of n moles of reactants. In regards to the term n, is this value the sum of the stoichiometric coefficients of all the products, and then all the reactants, or do you only take the moles of certain things like liquid and solids and not gas. I want to make sure because I know gases may sometime behave differently.

Thanks.

### Re: Understand equation

Posted: **Sun Feb 11, 2018 4:33 pm**

by **ConnorThomas2E**

You multiply the standard reaction entropy for the molecule by the stoichiometric coefficient given to you by the reaction. It does not matter if it is a solid, liquid, or gas. you multiply the standard reaction enthalpy of each substance by the amount of moles of that substance that are used during the reaction.

### Re: Understand equation

Posted: **Mon Feb 19, 2018 3:17 pm**

by **mayapartha_1D**

The equation takes into account all the moles no matter the state! So just take what you are given with the equation and the enthalpies and then subtract the sum of the reactants from the sum of the products.

Hope that helps.