Two beakers are joined by a salt bridge. One beaker contains aqueous solutions o

Question

Two beakers are joined by a salt bridge. One beaker contains aqueous solutions of potassium permanganate and manganous chloride, MnClh. The other beaker contains aqueous solutions of potassium dichromate and chromium(ilI) chloride. Both solutions are acidic with a pH of 6.20. Given that the molar concentrations o Mn0i, Mn2, Cr,0,, and Cr are 0.100 M, 0.0300 M, 0.0450M, and 0.100 M, respectively, what is the emf of this cell? [Hint: Remember, rather than balancing the equation by the half-reaction method, you may use already balanced half-reactions from Appendix E to get started. This is a verv straightforward nrahlam-dan's

Explanation / Answer

E°cell=E°Cathode-E°anode=(1.51-1.33)V=0.18 V

For permanganate half cell electron change is 5 and for dichromate is 6.

Now using Nernst equation we get

Ecell= E°cell-0.059/30* log{[Mn2+]^6[Cr2O72-]^5/[MnO4-]^6[CrCl3]^10}

Putting the value we get

Ecell=0.18-0.059/30*{6*log0.03+5*log0.045-6*log0.1-10*log0.1}=0.179 V

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---