Question

A brass plate of surface area 200 cm² on one side is electroplated with 0.10 mm thick silver layers on both sides using a 15 A current. Find the time taken to do the job. The specific gravity of silver is 10.5 and its atomic weight is 107.9 g mol⁻¹.

Answer 1

Given:
Current, i = 15 A
Surface area of the plate = 200 cm²,
Thickness of silver deposited= 0.1 mm = 0.01 cm
Volume of Ag deposited on one side = 200 × 0.01 cm³ = 2 cm³
∴ Volume of Ag deposited on both side = 4 cm³
Mass of silver deposited,
m = Volume × Specific gravity × 1000 = 4 × 10^-3 × 10.5 ×1000 = 42 kg
Using the formula, m = Zit, we get:
42 = Z_Ag × 15 × t
$$\begin{gathered} \Rightarrow t=\frac{42\times 96500}{107.9\times 15}\mathrm{s} \\ \Rightarrow t=2504.17\mathrm{s}=42\mathrm{minutes} \end{gathered}$$