ATAR Notes: Forum

VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: emiinaaa on October 14, 2012, 10:29:00 pm

Title: Help with Faraday's Laws Question
Post by: emiinaaa on October 14, 2012, 10:29:00 pm
When 289,500 Coulombs of electricity are passed through an electrolytic cell containing molten potassium chloride, what are the masses of potassium and chlorine produced?

Mr(K)=39 and Mr(Cl2)=71
Title: Re: Help with Faraday's Laws Question
Post by: TheRajinator on October 15, 2012, 04:27:32 pm
Q(C)=n(e)*96500
n(e)=289500/96500=3mol
n(K)=n(e)=3
therefore m(K)=Mr(K)*n(K)=39*3=117g
n(e)/2=n(Cl2)=1.5
m(Cl2)=Mr(Cl2)*n(Cl2)=71*1.5=106.5g
Title: Re: Help with Faraday's Laws Question
Post by: emiinaaa on October 15, 2012, 07:12:40 pm
Quote from: TheRajinator on October 15, 2012, 04:27:32 pm
n(K)=n(e)=3

Quote from: TheRajinator on October 15, 2012, 04:27:32 pm
n(e)/2=n(Cl2)=1.5

Sorry I don't understand how you came to this..
Title: Re: Help with Faraday's Laws Question
Post by: charmanderp on October 15, 2012, 07:21:19 pm
Quote from: emiinaaa on October 15, 2012, 07:12:40 pm
Quote from: TheRajinator on October 15, 2012, 04:27:32 pm
n(K)=n(e)=3

Quote from: TheRajinator on October 15, 2012, 04:27:32 pm
n(e)/2=n(Cl2)=1.5

Sorry I don't understand how you came to this..
Look in the electrochemical series and you'll find the mole ratio between electrons and potassium and electrons and chlorine.