A variable, the opposite external potential ( E ext ) is applied to the cell Z n   |   Z n 2 +…

A variable, the opposite external potential (Eext) is applied to the cell Zn | Zn2+ 1M∥Cu2+ 1 M| Cu, of potential 1.1 V. When Eext<1.1 V and Eext>1.1 V, respectively electrons flow from
  1. anode to cathode in both the cases.
  2. anode to cathode and cathode to anode.
  3. cathode to anode and anode to cathode.
  4. cathode to anode in both cases.

Solution

For a Daniel cell,

Ecell=0.34-(-0.76)=1.10 V.

When Eext<1.10 V, electrons flow from anode to cathode in the external circuit.

When Eext>1.10 V, electrons flow from cathode to anode in the external circuit (reverse reaction).

Asked in: JEE Main 2015 (10 Apr Online)

Practice more Electrochemistry questions on Aicharya