Question

Answer the following:

Predict whether the following reaction would occur spontaneously under standard state condition.

`"Ca"_(("s")) + "Cd"_(("aq"))^(2+) -> "Ca"_(("aq"))^(2+) + "Cd"_(("s"))`

Answer 1

`"Ca"_(("s")) + "Cd"_(("aq"))^(2+) -> "Ca"_(("aq"))^(2+) + "Cd"_(("s"))`

At anode: `"Ca"_(("s")) -> "Ca"_(("aq"))^(2+) + 2"e"^(-)`

At cathode: `"Ca"_(("aq"))^(2+) + 2"e"^(-) -> "Cd"_(("s"))`

From the electrochemical series we have,

`"E"_"Ca"^circ` = - 2.866 V and `"E"_"Cd"^circ` = - 0.403 V

For cell having Ca as anode and Cd as cathode.

`"E"_"cell"^circ = "E"_"Cd"^circ - "E"_"Ca"^circ`

= - 0.403 V - (- 2.866) V

`"E"_"cell"^circ` = 2.463 V

Emf of cell being positive, the given cell reaction is spontaneous.