Question

For the electrochemical cell:

M | M⁺ || X⁻ | X,

E⁰(M⁺ | M) = 0.44 V, E⁰(X | X⁻) = 0.33 V

Which of the following is TRUE for this data?

Options

• `"E"_"cell"^0` = −0.77V

• `"E"_"cell"^0` = 0.77V

• \[\ce{M^+ + X^- -> M + X}\] is a spontaneous reaction.

• \[\ce{M + X -> M^+ + X^-}\] is a spontaneous reaction.

Answer 1

\[\ce{M^+ + X^- -> M + X}\] is a spontaneous reaction.

Explanation:

Cell reaction: \[\ce{M + X -> M^+ + X^-}\]

Anode is M and cathode is X.

`"E"_"cell"^0 = "E"_"cathode"^0 - "E"_"anode"^0`

= 0.33 − 0.44

= −0.11 V

Since, `"E"_"cell"^0` is negative, the cell reaction is non-spontaneous.

∴ The reverse reaction, \[\ce{M^+ + X^- -> M + X}\] is the spontaneous reaction.