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Cancelling Out with Hess's Method

Posted: Sat Jan 26, 2019 9:05 pm
by Sophia Diaz - Dis 1B
In class we did an example with NO2 formation:

N2 + O2 --> 2NO
2NO + O2 --> 2NO2
----------------------
N2 + 2O2 --> 2NO2

The way we got the third and final reaction was by adding the first two and the 2NO's "canceled out."
I don't really understand how the 2NO's canceled out but the O2's did not. Why did only the 2NO's get canceled out in order to get the final equation?

Re: Cancelling Out with Hess's Method

Posted: Sat Jan 26, 2019 9:48 pm
by Theodore_Herring_1A
The 2NOs cancel out because one is a reactant and the other is a product. The O2s do not cancel out since they are both reactants, and thus they are added together.

Re: Cancelling Out with Hess's Method

Posted: Sun Jan 27, 2019 1:25 am
by Ethan Yi 1K
the 2NO's are on opposite sides of the equation and therefore will cancel out. however, the O2's are on the same side, so you add them together.

Re: Cancelling Out with Hess's Method

Posted: Sun Jan 27, 2019 9:40 pm
by Jocelyne Milke 1G
You can only cancel things out when you have the same compound on the reactants side and the products side.