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Help with a balanced equation

Posted: Mon Jan 14, 2008 9:39 pm
by wedge-7
Hi all! I'm actually new here and was hoping someone could help me decipher what exactly this question is asking.

Write a balanced equation for the reaction of dichromate ion, Cr2O7 -2 with chromium metal in aqueous acidic solution, to give Cr3+ and water.

I'm just a little confused with what exactly chromium metal in aqueous acidic solution means, if it was just Cr or if the aqueous acidic solution actually plays apart in the equation?

Any help would be much appreciated.

Thanks!

Posted: Mon Jan 14, 2008 10:16 pm
by holyland
in my opinion, the action is as following
Cr2O7 2- + Cr =>Cr3+

and the Cr3+ will Disperse to the solution. And this is usefull for the reaction.

but if the solution is Based(PH>7), there will be OH- in the solution, so the following reaction will Cr3+ + 3OH- == Cr(OH)3! .

and this reaction will stop the first reaction.
:P


my personal web: www.chem-zone.com

Posted: Mon Jan 14, 2008 10:53 pm
by wedge-7
thanks for the repsonse, but i'm still a tad confused with what exactly the dichromate reacting with a chromium metal in aqueous acidic solution means exactly.

is that just Cr2O72- + Cr -> Cr+3 + H2O ...?

So the aqeous acidic solution plays no real part before the balancing?