Question

Ratio of number of faradays of electricity required to deposit magnesium, aluminium and sodium in equimolar ratio an electrolysis of their respective molten salts is:

• A. 2 : 3 : 2
• B. 2 : 1 : 1
• C. 2 : 3 : 1
• D. 4 : 6 : 1

Answer 1

Answer: (C)

2 : 3 : 1

Electrode reactions involved are
$M{g}^{+2}+2e^{-}\to Mg$
$A{l}^{+3}+3e^{-}\to Al$
$N{a}^{+}+e^{-}\to Na$
1 mole of $Mg$ requires 2 Faradays.
1 mole of $Al$ requires 3 Faradays.
1 mole of sodium requires 1 Faraday.
Ratio of number of Faraday = $2:3:1$