platinum

2. (a) Devise electrochemical cells in which the following reactions occur: (i) Zn(s) Cu2+(aq) Cu(s) + Zn2+(aq) (ii) Fe3+(aq) + Cr²+(aq) Fe2+(aq) + Cr3+(aq) (iii) Ag+(aq) + (aq) Agl(s) (b) For the electrochemical cell: Pt Fe³ (aq), Fe2(aq) || Br (aq) | Br2(g), (1 atm) | Pt, The standard electrode potential of the cathode is 1.065 V and the anode, 0.771 V at 298 K. Calculate: (6) (i) the standard e.m.f. of the cell and hence deduce the cell reaction, (6) (ii) the e.m.f. of the cell when a = 0.06, a = 0.01 and a = 0.03, (6) Br (iii) the equilibrium constant for the cell reaction at 298 K. (7)

Ff.39.

V. (6)H in 0.20 bar Salt bridge |(ag) H(ao) Pt Ag wire coated with Agi(s) Nal (0.10 M) HCI (0.10 M) (a) Write the line notation for this cell. (b) Calculate the potential for each half-cell and the cell voltage E. (c) Write the spontaneous net cell reaction.