Posted by ill matic on .
What mass of chromium could be deposited by electrolysis of an aqueous solution of Cr2(SO4)3 for 180.0 minutes using a constant current of 10.0 amperes? (One faraday = 96,500 coulombs.)

chemistry 
DrBob222,
coulombs = amperes x seconds.
C = 10A x 180 min x (60 s/min) = ??
It takes 96,500 coulombs to deposit 1 mol Cr/3 or 52.01/3 grams. 
chemistry 
ill matic,
Why did you divide the molar mass by 3?

Chemistry 
Amanda,
You would use stoichiometry. Multiply the amps by the time (convert minutes to seconds, then you end up with Coulombs. The stoichiometry should look a little like this...
(amps x time)(1 F/96,500 coulombs)(1 mol e/1 F)(3 mol e/1 mol Cr)(Molar Mass of Cr/1 mol Cr) ... I got the 3 mol e from balancing the halfcell reactions. I got my answer to come out to 19.4 grams Cr