Question

In order to restore an antique car, a 0.2 m2 bumper for a car is to be chrome plated. The current is set to be 10 A. Determine the thickness of the Cr layer after 30 minutes. Discuss the chrome plating process.

Answer 1

Current = 10 A

Time = 30 min = 1800 s

Using Faraday's law of electrolysis -

m = (It / F)(M / z)

= (10*1800 / 96485)(52 / 6)

= 1.61 g

Density of chromium = 7.19x10⁶ g/m3

Volume of metal used = 1.61 g / 7.19x10⁶ g/m3

= 2.24x10^-7 m3

Area of bumper = 0.2 m2

Thickness of Cr layer = 2.24x10^-7 m3 / 0.2 m2

= 1.12x10^-6 m

= 1.12 m

Chrome plating process involves the followinf steps -

1 - Degreasing to remove heavy soiling

2 - Manual cleaning to remove all residual traces of dirt and surface impurities.

3 - Various pretreatments depending on the substrate.

4 - Placement into the chrome plating vat, where it is allowed to warm to solution temperature.

5 - Application of plating current for the required time to attain the desired thickness.