[Atome]

Hello everyone,

I just want to confirm my understanding of the following question.

Thank you!

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1. All compounds are gases:

2NO₂ N₂ + 2O₂

If N₂ is removed from the above question, in what direction will the equilibrium shift?

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The answer is a shift to the right. I just want to verify the following:

1. If the equilibrium shifts to the right, the forward reaction will occur. If the equilibrium shifts to the left, the reverse reaction will occur.

2. Therefore, in the above reaction, the shift would be to the right since the forward reaction is favoured. Nitrogen dioxide must decompose to replace the N₂ removed?

[macman104]

Correct.

[Mitch]

Yes, sounds good.

[azmanam]

The only part of your answer I would tweak is this:

since the forward reaction is favoured.

The equilibrium does shift to the right.  But not so much because the forward reaction is more favored.  It shifts to the right because you've disrupted the equilibrium.  The system seeks to restore the equilibrium, thus more of the reactant converts to product.  When the newly formed product is subsequently removed, the equilibrium is disrupted again.  The system again seeks to restore equilibrium... repeat.

The forward reaction could theoretically be severely disfavored and Le Chatelier's principle will still drive the reaction to the right.  The equilibrium could favor the left side 1000:1.  1000 molecules of NO₂ could exist for every one molecule of N₂.  But once that 1 molecule of N₂ is removed, the equilibrium disruption causes another 2 molecules of NO₂ to decompose.  Now the equilibrium is something like 998:1.  This will continue until all of the reactant is used up.

In fact, this principle is often used to drive unfavorable reactions to completion.

http://en.wikipedia.org/wiki/Le_Chatelier%27s_Principle