Consider the figure given above and answer the following questions:

(a) What is the direction of flow of electrons?

(b) Which one is anode and which one is cathode?

(c) What will happen if the salt bridge is removed?

(d) How will concentration of Zn²⁺ and Ag⁺ ions are affected when the cell functions?

(e) How will concentration of these ions be affected when the cell becomes dead?

OR

 Define electrochemical cell.

For a cell Ag (s)| AgNO₃ (0.01M)|| AgNO₃ (1.0M)| Ag(s)

(i) Calculate the emf of the cell at 25 C°.

(ii) Write the net cell reaction.

(iii) Will the cell generate emf, when two concentrations become equal?

(a) Electrons flow from Zn to Ag plate.

(b) Zn acts as anode and Ag acts as cathode

(c) Cell will stop functioning

(d) Concentration of Zn²⁺ ions will increase and that of Ag+ ions will decrease.

(e) No change

OR

The cell in which chemical energy changes to electrical energy is called electrochemical cell.

Electrochemical reaction is

$$\begin{gathered} \mathrm{Ag}+{\mathrm{Ag}}^{+}\to {\mathrm{Ag}}^{+}+\mathrm{Ag} \\ \left(1\mathrm{M}\right) \left(0.1 \mathrm{M}\right) \\ {\mathrm{E}}_{\mathrm{cell}}^{*}={\mathrm{E}}_{{\mathrm{Ag}}^{+}/\mathrm{Ag}}^{*}-{\mathrm{E}}_{{\mathrm{Ag}}^{+}/\mathrm{Ag}}^{*}=0 \\ {\mathrm{E}}_{\mathrm{cell}}={\mathrm{E}}_{\mathrm{cell}}^{*}-\frac{0.059}{\mathrm{n}}\log \frac{\left[0.01\right]}{\left[1\right]} \\ =0.059 \log {10}^2 \end{gathered}$$

(i) ${\mathrm{E}}_{\mathrm{cell}}=2\times 0.059=0.1182 \mathrm{V}$

(ii) Net cell reaction is ${\mathrm{AgNO}}_3\left(\mathrm{M}\right)\to {\mathrm{AgNO}}_3\left(0.01 \mathrm{M}\right)$

(iii) The cell would not generate emf. If the concentrations are equal, then

$$\begin{gathered} {\mathrm{E}}_{\mathrm{cell}}={\mathrm{E}}_{\mathrm{cell}}^{*}-\frac{0.0591}{\mathrm{n}}\log \frac{\left[{\mathrm{Ag}}^{+}\right]}{\left[{\mathrm{Ag}}^{+}\right]} \\ =0-\frac{0.0591}{\mathrm{n}}\log 1=0 \end{gathered}$$