Le Chatelier's

[waywardtigerlily]

Hello, I was wondering if I could get some help, or at least lead in the right direction.

I am working on my lab report for Nitration of Bromobenzene and there is a question that is:

Precipitation of the mononitration product of bromobenzene prevents dinitration from occuring. Explain how this experimental result is an application of the LeChatelier's principle and given your prediction, write a chemical equation for the equilibrium involving reaction of sulfuric and nitric acids.

I am a little too lost on this to even begin. And help would be great
Thanks,
K

[imrober]

Hi,

I'm not sure of the equation you'd need, but I can say that the main idea behind Le Chatelier's principle is that:

A change in any of the main components that are involved in establishing an equilibrium (such as everything in solution) will cause the equilibrium to shift in order to counteract the change.

So if something (like the mononitrile substituted ring) is leaving the solution, the equilibrium of the reaction will shift to produce MORE of the precipitating product.

Hope that helps,

IR

[bw800402]

the equation will show nitric acid plus sulfuric acid yielding hydronium, nitronium, and deprotonated sulfuric acid. Then bromobenzene reacts w/ nitronium via electrohilic aromatic substitution.

to reiterate Le Chatlier as explained already-- a normal reaction will reach an equilibrium in which no more product is formed and no more reactants converted without addition of more reactant or removal of product. Howevere precipitation removes said product from solution allowing more product to be formed and pushin the reaction to the right (from reactant to product).