Cancelling Out with Hess's Method

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Sophia Diaz - Dis 1B
Posts: 73
Joined: Fri Apr 06, 2018 11:02 am
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Cancelling Out with Hess's Method

Postby Sophia Diaz - Dis 1B » Sat Jan 26, 2019 9:05 pm

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?

Theodore_Herring_1A
Posts: 60
Joined: Fri Sep 28, 2018 12:29 am

Re: Cancelling Out with Hess's Method

Postby Theodore_Herring_1A » Sat Jan 26, 2019 9:48 pm

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.

Ethan Yi 1K
Posts: 62
Joined: Fri Sep 28, 2018 12:28 am

Re: Cancelling Out with Hess's Method

Postby Ethan Yi 1K » Sun Jan 27, 2019 1:25 am

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.

Jocelyne Milke 1G
Posts: 73
Joined: Fri Sep 28, 2018 12:25 am

Re: Cancelling Out with Hess's Method

Postby Jocelyne Milke 1G » Sun Jan 27, 2019 9:40 pm

You can only cancel things out when you have the same compound on the reactants side and the products side.


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