December 26, 2024, 11:44:03 AM
Forum Rules: Read This Before Posting


Topic: Daniell-Jacobi galvanic cell problem  (Read 6058 times)

0 Members and 1 Guest are viewing this topic.

Offline Juozukas

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Daniell-Jacobi galvanic cell problem
« on: January 04, 2008, 06:02:25 AM »
hello,
i had to solve this problem:

Compose the conditional scheme of a Daniell-Jacobi galvanic cell in which the zinc and iron electrodes are immersed into the solutions of their salts(Zn2+ and Fe 2+). Write the equations of the reactions taking place on the electrodes. Calculate the concentration of the Fe2+ ions if the electromotive force is 0 and the concentration of Zn2+ is 0,001mol/l.

I tried to solve the problem, unfortunately i did something wrong. Here is how i calculated:

http://img201.imageshack.us/img201/5207/problemzy5.jpg (I'm sorry for making an image, but i don't know any other way to show you how i did it)

The answer 13,9 seems not logical to me, that's why I'm asking you help. Tell me where is the mistake, it would be really nice if you would correct it :)

Offline Kryolith

  • Full Member
  • ****
  • Posts: 269
  • Mole Snacks: +19/-4
  • Gender: Male
Re: Daniell-Jacobi galvanic cell problem
« Reply #1 on: January 05, 2008, 04:11:09 PM »
EC=-0.44 V + 0.059 V/2*lg [Fe2+]
EA=-0.76 V + 0,059 V/2*lg(0.001) = -0.8485 V

EC-EA=-0.44 + 0.0295 lg [Fe2+] + 0.8485 = 0
==> lg [Fe2+]=-13.847
==> [Fe2+]=1.42 * 10-14 mol/l

Offline Juozukas

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Re: Daniell-Jacobi galvanic cell problem
« Reply #2 on: January 06, 2008, 11:31:11 AM »
EC=-0.44 V + 0.059 V/2*lg [Fe2+]
EA=-0.76 V + 0,059 V/2*lg(0.001) = -0.8485 V

EC-EA=-0.44 + 0.0295 lg [Fe2+] + 0.8485 = 0
==> lg [Fe2+]=-13.847
==> [Fe2+]=1.42 * 10-14 mol/l


where did you get the 1.42 from?

Offline Kryolith

  • Full Member
  • ****
  • Posts: 269
  • Mole Snacks: +19/-4
  • Gender: Male
Re: Daniell-Jacobi galvanic cell problem
« Reply #3 on: January 06, 2008, 12:12:01 PM »
lg x = y ==> x=10y
10-13.847=1.42 * 10-14

Sponsored Links