Question

a) Write the equations for the electrode reactions for the electrolysis of an aqueous solution of lithium bromide. Hydrogen gas forms at one electrode and liquid bromine forms at the other electrode. Identify the anode and the cathode. Write the overall cell reaction.

b) write the half cell reactions, the overall cell reaction; and identify the anode and the cathode for the voltaic cell represented as follows:

Cr (s) | Cr 3+ (1M) || Hg 2+ (1M) | Hg (l) | Pt

using a table of standard reduction potentials, calculated the cell voltage

Answer 1

a   2LiBr (aq) ------------------->2 Li^+ (aq) + 2Br^-

    at anode

      2Br^-       ------------------> Br2(g) + 2e^-

     at cathode

    2H2O(l) --------------> H2 (g)+ 2OH^-(aq)

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2Br^- (aq) + 2H2o(l) ------------> Br2(aq) + H2(g) +2OH^- (aq) over all reaction

b.

       2Cr (s) --------------> 2Cr^3+ (aq) + 6e^-        E0   = 0.74v

       3Hg^2+ (aq) + 6e^- -----------> 3Hg(aq)         E0 = 0.85bv

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2Cr(s) + 3Hg^2+ (aq) ---------------> 2Cr^3+ (aq) + 3Hg(aq)     E0 cell = 1.59v

                n = 6

Ecell   =   E0cell- 0.0592/n log[Cr^3+]^2/[Hg^2+]^3

            = 1.59 - 0.0592/6 log(1)^2/(1)^3

             = 1.59v >>>>>answer