Calculating \Delta_H for a Reaction: A Simple Guide

[courtrigrad]

Hello all

Let's say we are given:

$$CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$$

We want to find $$\Delta_H$$ for the entire reaction.

Would I just use the formula:

$$\sum _i \Delta_H_i - \sum _j \Delta_H_j$$? In other words just look up enthalpies in book and subtract enthalpy of reactants from enthalpy of products?

Thanks

 

[dextercioby]

Hello all

Let's say we are given:

$$CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$$

We want to find $$\Delta_H$$ for the entire reaction.

Would I just use the formula:

$$\sum _i \Delta_H_i - \sum _j \Delta_H_j$$? In other words just look up enthalpies in book and subtract enthalpy of reactants from enthalpy of products?

Thanks

IIRC,that's how it goes.To find the reaction enthalpy,u need to know the creation enthalpies for each of the components from the reaction.Pay attention with the signs.

Daniel.

 

[wais]

for creating this guide, it's very helpful!

Hello! Yes, you are correct in using the formula \sum _i \Delta_H_i - \sum _j \Delta_H_j to calculate \Delta_H for this reaction. The \Delta_H values for each species can be found in a reference book or online database. Just make sure to use the correct units and to account for the coefficients in the balanced chemical equation. I'm glad the guide was helpful for you!