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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: magnus on January 27, 2019, 05:10:09 PM

Title: Electrolyzing a solution
Post by: magnus on January 27, 2019, 05:10:09 PM

Hi I have a problem with this:
Electrolyzing a solution of a ruthenium sale for 500 seconds with a current of 120 mA deposited 31.0 g of metallic ruthenium. How much is the
oxidation number of ruthenium in the salt used?

i=Q/t => Q=0.12*500= 60 C

m=Q/F * PM/z  =>  z=Q*PM / F*m = 0.002  ???

The result is impossible... >:( >:(

Title: Re: Electrolyzing a solution
Post by: Borek on January 27, 2019, 06:19:47 PM

Are you sure it is 31 g, and not 31 mg?

Title: Re: Electrolyzing a solution
Post by: magnus on January 28, 2019, 02:43:28 AM

the text of the question reported those quantities, but I do not think they are real

Title: Re: Electrolyzing a solution
Post by: Enthalpy on January 28, 2019, 08:45:27 AM

Either 31mg and 120mA, or 31g and 120A. Or even 500ks.

Don't laugh. Some publications do use ks rather than hours and months. I saw "3.6ks" recently in a metallurgy paper.

Title: Re: Electrolyzing a solution
Post by: sjb on January 28, 2019, 08:53:43 AM

Quote from: Enthalpy on January 28, 2019, 08:45:27 AM

Some publications do use ks rather than hours and months. I saw "3.6ks" recently in a metallurgy paper.

Makes the maths easier :)