April 11, 2021, 05:40:45 AM
Forum Rules: Read This Before Posting


Topic: Galvanic cells  (Read 3961 times)

0 Members and 1 Guest are viewing this topic.

777888

  • Guest
Galvanic cells
« on: October 28, 2004, 06:13:17 PM »
A student makes 4 galvanic cells by having Cu as a electrode in each cell, and has the other electrode as Pb, Mg, Zn, Fe, respecctively. Each half-cell has its corresponding electrolyte. A salt bridge with KNO3 and a wire to the elctrodes are connected. The positive terminal of a voltmeter is put on the Cu and the negative terminal is put on Pb, Mg, Zn, Fe respectively to measure the voltage. He then arrange the cells in order from smallest to largest cell voltage. Why is the copper electrode always used?

I don't get this question... can somebody explain to me? I would appreciate!
« Last Edit: October 28, 2004, 06:20:07 PM by 777888 »

Offline Donaldson Tan

  • Editor, New Asia Republic
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3178
  • Mole Snacks: +261/-13
  • Gender: Male
    • New Asia Republic
Re:Galvanic cells
« Reply #1 on: October 28, 2004, 07:39:03 PM »
electrons flow from low to high potential. if you want electrons to flow from Pb/Mg/Zn/Fe electrode to another metal electrode, that electrode must be made of a metal that has a lower redox potential than Pb/Mg/Zn/Fe. Copper fulfills this condition.
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Demotivator

  • Guest
Re:Galvanic cells
« Reply #2 on: October 28, 2004, 07:40:43 PM »
Since the student is comparing the potential strengths of the other half cells, the comparisons should be made with reference to a constant, in this case the copper half cell.

Sponsored Links