TEXTBOOK 14.57

Yiwei Zhou 2I
Posts: 21
Joined: Fri Sep 29, 2017 7:07 am

TEXTBOOK 14.57

Aqueous solutions of (a) Mn2; (b) Al3; (c) Ni2; (d) Au3 with concentrations of 1.0 molL1 are electrolyzed at pH  7. For each solution, determine whether the metal ion or water will be reduced at the cathode.

What is the standard reduction potential of water?
2H2O + 2e- = H2 + 2OH-  -0.83V
But the solution manual shows that the reduction potential of water is -0.42V.

Could someone explain this? Thanks a lot!

Dylan Davisson 2B
Posts: 50
Joined: Thu Jul 27, 2017 3:00 am
Been upvoted: 2 times

Re: TEXTBOOK 14.57

Before the questions in the electrolysis section chapter 14, there is a statement saying to use the potentials listed in the standard potentials chart, except for the reduction and oxidation of water at pH=7. Then they say that the equation with water as a reactant (being reduced) has a potential of E=-0.42 V at pH=7, and the equation with water as a product (being oxidized) has a potential of E=+0.82 V at pH=7. In these questions, just use those potentials for water, and it should work out.

Return to “Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams”

Who is online

Users browsing this forum: No registered users and 2 guests