Question

The quantity of electricity required to deposit 1.15 g of sodium from molten NaCl (Na = 23, Cl = 35.5) is :

• A. 1 F
• B. 0.5 F
• C. 0.05 F
• D. 1.5 F

Answer 1

Answer: (C)

0.05 F

Mass of Na is divided with its atomic mass to obtain number of moles.
Number of moles of Na $=\frac{1.15}{23}=0.05$ moles.
$N{a}^{+}+e^{-}\to Na$
Thus, deposition of 1 mole of Na will require 1 mole of electrons which corresponds to 1 Faraday of electricity. The, deposition of 0.05 moles (1.15 g) of Na will require 0.05 moles of electrons which corresponds to 0.05 Faraday of electricity.