## How to use Hess’s Law

$\Delta U=q+w$

veneziaramirez 3I
Posts: 57
Joined: Fri Sep 29, 2017 7:07 am

### How to use Hess’s Law

In toolbox 8.1, it says to cancel species that appear on both sides of the equation and to add substances on the opposite side of the arrow. However in the example 8.16 provides on pg. 292, it does the opposite. The O2’s are added yet are on the same side of the arrow and the CO’s are subtracted yet are on the opposite sides of the arrow? Which is the correct way?

MorganYun1H
Posts: 59
Joined: Thu Jul 13, 2017 3:00 am

### Re: How to use Hess’s Law

You always add whatever is on the same side of the equations and subtract the ones opposite. That's why the CO2's cancel off.