Question

An electrochemical cell can behave like an electrolytic cell
when ......
(a) E꜀ₑₗₗ = 0 (b) E꜀ₑₗₗ > Eₑₓₜ
(c) Eₑₓₜ > E꜀ₑₗₗ (d) E꜀ₑₗₗ = Eₑₓₜ

Answer 1

Answer:

ANSWER

We can study the effect of opposing potential applied to a galvanic cell as follows.

1) When E_{external}< 1.1VE

external

<1.1V

In a galvanic cell, if an external opposite potential is applied and increased slowly, we find that the reaction continues to take place till the opposing voltage reaches the value 1.1 V.

2) When E_{external}= 1.1VE

external

=1.1V

When the external voltage is 1.1V the reaction stops altogether and no current flows through the cell.

3) When E_{external}> 1.1VE

external

>1.1V

Any further increase in the external potential again starts the reaction but in the opposite direction. It now functions as an electrolytic cell, a device for using electrical energy to carry non-spontaneous chemical reactions.

VIDEO EXPLANATION

Answered on November 22, 2019 by

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1 Verified Answer

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Answer 2

(There are some errors in the question. The correct question will be read as:

An electrochemical cell can behave like an electrolytic cell when

(a) $\[{E_{cell}} = 0\]$                          (b) $\[{E_{cell}} > {E_{ext}}\]$

(c) $\[{E_{ext}} > {E_{cell}}\]$                     (d) $\[{E_{cell}} = {E_{ext}}\]$)

An electrochemical cell can behave like an electrolytic cell when $\[{E_{ext}} > {E_{cell}}\]$. Thus, the correct option is (c) $\[{E_{ext}} > {E_{cell}}\]$.

Explanation:

• An electrochemical cell changes chemical energy to electrical energy while an electrolytic cell changes electrical energy to chemical energy.
• In the first case when $\[{E_{cell}} = 0\]$, equilibrium is maintained and the potential of both cathode and anode are equal.
• In the second case when $\[{E_{cell}} > {E_{ext}}\]$, the electrochemical cell reaction will take place till $\[{E_{cell}}\]$ becomes equal to $\[{E_{ext}}\]$.
• When $\[{E_{cell}} = {E_{ext}}\]$, the reaction stops and does not proceed further and no current flows through the circuit.
• When $\[{E_{ext}} > {E_{cell}}\]$, the reaction occurs in the opposite direction. This means the cell starts converting electrical energy to chemical energy.
• Thus, it behaves like an electrolytic cell.
• Hence, an electrochemical cell can behave like an electrolytic cell when $\[{E_{ext}} > {E_{cell}}\]$.

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