Electroplating

Electroplating

• The electroplating of an object with metal is accomplished using an electrolytic cell.

• There are some basic rules for electroplating.

The object to be plated must always be the cathode in the electrolytic cell. Thus, it must always be connected to the negative pole of the electric source.

The anode in the electrolytic cell must be made from the plating metal.

The electrolyte used in the electrolytic cell must contain the cation of the plating metal.

offAg

AgNO3(aq)

Ag+

Ag+

Ag+

Ag+

Ag+

- +power source

on

Ag

Ag

Ag NO3-

NO3-

NO3-

NO3-

NO3-

e-

e-

e- e- e-

e-

e-

e-

Ag

AgAg+

Ag+

Copper spoon

Electroplating

cathodeanode

ElectroplatingEx.1) Electrons enter into the ____ (+/-) pole of a battery

and exit out from the ____(+/-) pole of the a battery.

Ex.2) When electroplating, the electrolyte used needs to contain the same metal as the _________________________

Ex.3) In the electrolytic process used to plate pure copper onto the surface of a material, the material should be connected in the electroplating device as the

(1) cathode which is positive (2) cathode which is negative(3) anode which is positive(4) anode which is negative

+_

platingmetal

Electroplating

Ex.4) Which of the following cells is set up properly to electroplate a silver spoon with gold?

(1) (3)

(2) (4)

battery- +

AgNO3(aq)

Ag(s)

battery- +

Au(NO3)3(aq)

Au(s)

battery+ -

AgNO3(aq)

Ag(s)

battery+ -

Au(NO3)3(aq)

Au(s)

Electroplating

Ex.5) Complete the set up in order to electroplate the piece of zinc pipe with copper.

[DRAW LINES TO REPRESENT THE WIRES]

The metal strip is made of

____________

What salt would you add?

____________

Battery

+ -

copper

Cu(NO3)2

Electroplating

Ex. (6) The diagram below shows a key to be plated with silver in an electrolytic cell. Draw lines from

the battery to the key and from the battery to the silver electrode to correctly set-up the electrolytic cell.

+ -

BatterySilverelectrode

AgNO3 solution

A B

Electroplating

Ex. (7) Given the reduction reaction for the cell above:

Ag1+(aq) + 1e- → Ag(s)

This reaction occurs at

(1) A, which is the anode

(2) A, which is the cathode

(3) B, which is the anode

(4) B, which is the cathode

+ -

BatterySilverelectrode

AgNO3 solution

A

B