Concentration and direction of reaction


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GraceChen2A
Posts: 14
Joined: Fri Sep 26, 2014 2:02 pm

Concentration and direction of reaction

Postby GraceChen2A » Tue Feb 03, 2015 6:48 pm

Question 99 asks that a) If you were to construct a concentration cell in which one half-cell contains 1.0 M CrCl3 and the other half-cell 0.0010 M CrCl3, and both electrodes were chromium, at which electrode would reduction spontaneously take place? This would be the side with the highest concentration, because it would have the highest electrode potential and the higher the E value, the more likely reduction is able to take place. I understand this part

However b) asks "How will each of the following changes affect the cell potential? Adding 100mL pure water to the anode compartment." The solutions manual says that the reaction is Cr3+ (1.0 M) -> Cr3+ (0.0010 M). I'm confused as to what this equation means. Does this mean the electrons travel toward the 0.0010M side?

Chem_Mod
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Re: Concentration and direction of reaction

Postby Chem_Mod » Wed Feb 04, 2015 1:19 pm

Refer to course reader pg.49 where it says always make the lower conc the product and shows the rxn for silver, very similar to the one for chromium in problem 99.

Justin Le 2I
Posts: 142
Joined: Fri Sep 26, 2014 2:02 pm

Re: Concentration and direction of reaction

Postby Justin Le 2I » Wed Feb 11, 2015 1:27 pm

The way I think of it is the concentration on the reactants side is decreasing and the concentration on the products is increasing. So the side with 1.0 M is decreasing and the side with 0.0010 M is increasing.


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