Instant Notes: Analytical Chemistry

the copper electrolysis cell has two electrodes placed in an acidified aqueous

solution of a copper salt.

Example

If a current of 0.123 amps is passed through a copper electrolysis cell for one

hour, how much copper will deposit?

0.123 A =0.123 C s-^1

Since 1 hour =3600 s, therefore, It =442.8 C are passed.

1 mole of copper is 63.5 g, which requires 2F = 2 ¥ 96485 C, so 442.8 C deposit

63.5¥ 442.8/(2¥ 96485) g =0.1457 g.

It is possible to deposit metals onto an electrode quantitatively, using the

technique of electrogravimetry, although this is not often used. Electrolysis may

also be used to generate reagents to react with analytes, and this is referred to as

coulometry.

C2 – Electrochemical reactions 65