(b) (i)The e.m.f. of the cell was measured as 0.62 volts. Taking the standard electrode potential of Cu/Cu2+ as = +0.34 volts, calculate the standard potential of the Co/Co2+ system. Be careful to indicate whether your answer is positive or negative.

(ii) State the direction in which the electrons flow. [3]
(c) (i) What would you see if pieces of copper metal were added to an aqueous solution of cobalt
chloride?
(ii) What would you see if pieces of cobalt metal were added to an aqueous solution of copper (II)
chloride?

Co ==> Co^2+ + 2e Eo = ?

Cu^2+ + 2e ==> Cu Eo = 0.34
-----------------------------
Co + Cu^2+ ==> Cu + Co^2+ E = 0.62
So Eo Co + Eo Cu^2+ = Ecell = 0.62
Therefore, Co ==> Co^2+ must be +0.28 v because 0.28 + 0.34 = 0.62

The half cell releasing electrons is the anode and that is negative.
The other half cell is the cathode and is positive. Electrons flow from the negative to the positive.
If you add Co metal you will see Cu plating out on it. If you add Cu metal nothing happens.

(b) (i) To calculate the standard potential of the Co/Co2+ system, we can use the equation:

Standard potential of the cell (Ecell) = Standard potential of the cathode - Standard potential of the anode

Ecell = Ecathode - Eanode

Given:
Ecell = 0.62 V (measured)
Standard potential of Cu/Cu2+ system (Ecathode) = +0.34 V

Rearranging the equation, we get:

Eanode = Ecathode - Ecell

Eanode = +0.34 V - 0.62 V
Eanode = -0.28 V

Therefore, the standard potential of the Co/Co2+ system is -0.28 V (negative).

(ii) Electrons always flow from the anode to the cathode in an electrochemical cell. So in this case, the electrons would flow from the Co/Co2+ system (anode) to the Cu/Cu2+ system (cathode).

(c) (i) When pieces of copper metal (Cu) are added to an aqueous solution of cobalt chloride (CoCl2), a redox reaction occurs. Copper metal loses electrons to form copper ions (Cu2+), while cobalt ions (Co2+) gain electrons to form cobalt metal (Co). The copper metal will gradually dissolve in the solution, and the color of the solution will turn from blue to green as copper ions are formed.

(ii) When pieces of cobalt metal (Co) are added to an aqueous solution of copper (II) chloride (CuCl2), a redox reaction occurs. Cobalt metal loses electrons to form cobalt ions (Co2+), while copper ions (Cu2+) gain electrons to form copper metal (Cu). The cobalt metal will gradually dissolve in the solution, and the color of the solution will turn from blue to brown as copper metal is formed.