Question

One Faraday of charge was passed through the electrolytic cells placed in series containing solutions of Ag⁺, Ni²⁺ and Cr³⁺ respectively. The amounts of Ag (At. mass = 108), Ni (At. mass = 59) and Cr (At. mass = 52) deposited will be:

Options

• Ag	Ni	Cr
  108 g	29.5 g	17.5 g

• Ag	Ni	Cr
  108 g	59.0 g	52.0 g

• Ag	Ni	Cr
  108 g	108.0 g	108.0 g

• Ag	Ni	Cr
  108 g	117.5 g	166.0 g

Answer 1

Ag	Ni	Cr
108 g	29.5 g	17.5 g

Explanation:

When 1 Faraday (F = 96500 C) of charge is passed through electrolytic cells in series, the same quantity of electricity flows through each cell. The mass deposited is proportional to the equivalent weight of each metal.

Mass deposited = Equivalent weight

= `"Atomic mass"/n`

Where n is the number of electrons exchanged (valency).

For silver (Ag⁺): n = 1, Atomic mass = 108

Mass = `108/1` = 108 g

For nickel (Ni²⁺): n = 2, Atomic mass = 59

Mass = `59/2` = 29.5 g

For chromium (Cr³⁺): n = 3, Atomic mass = 52

Mass = `52/3` = 17.33 g ≈ 17.5 g