Finding standard reaction enthalpy

[EmilyC_3D]

When calculating standard reaction, should we always be subtracting the sum of the standard molar entropy of reactants from the sum of the standard molar entropy of products or is there another method? Will we ever need to find standard molar entropy or will that be given?

[Kailani_Dial_2K]

I think that the only way to calcualte standard molar entropy is products- reactants. However, there are multiple ways to calculate entropy in general, so be sure to look at what the question is asking for.

[Daniela Santana 2L]

Hi! In order to calculate the standard reaction enthalpy you just find the sum of the products and the sum of the reactants and subtract them. It should look like (sum of products - sum of reactants), this method should help you find the standard reaction enthalpy. I hope this helped!

[Andersen Chu 2H]

It should be products - reactants, but they might ask you to calculate the standard molar entropy of a species by giving you the entropy of a reaction and the other species of that reaction to make you use a little bit of algebra, but in general the values are found experimentally so there isn't some sort of process we need to know about calculating standard molar entropies

[Olivia Monroy 1A]

Products minus reactants is used to calculate the standard reaction enthalpy. Sum the enthalpy value of each product and each reactant, multiply by number of moles, and because enthalpy is a state function you can do final - initial (products - reactants).

[Alejandro Gonzalez 2G]

The standard molar enthalpy is either given to you or found in the standard enthalpy of formation of the products minus the standard enthalpy of formation of the reactants.

[Samir 3I]

Because we are dealing with standard molar enthalpy, which is a standard measurement under specific/controlled conditions the only way to really calculate it is to use the known standard enthalpies of the products and reactants. Subtract the sum of the standard molar enthalpies of the products and subtract the sum of the standard molar enthalpies of the reactants. I suppose you could also find the standard molar enthalpy through a calorimetry experiment of your own.

[Mackenzie Stockton 2H]

to find standard reaction enthalpy,

find the total standard enthalpy of formation of the products (summation) - standard enthalpy of formation of reactants