Q16E - Chemistry (OpenStax)

Question

Why is it necessary to keep the chlorine and sodium, resulting from the electrolysis of sodium chloride, separate during the production of sodium metal?

Step-by-Step Solution

Answer

To prevent the spontaneous formation of sodium chloride.

Step 1: Representative metals

These metals are found primarily in minerals, with lithium found in silicate or phosphate minerals, and sodium and potassium found in salt deposits formed by evaporation of ancient seas and in silicates. 

Except for beryllium, alkaline earth metals occur as silicates, carbonates, and sulphates.

Step 2: Electrolysis of NaCl

When an electric current passes through a concentrated sodium chloride solution, hydrogen gas is formed at the negative electrode, chlorine gas is formed at the positive electrode, and a sodium hydroxide solution is formed.

The reaction of electrolysis is:

\({\bf{2NaCl}}\left( {\bf{l}} \right) \to {\bf{2Na}}\left( {\bf{s}} \right){\bf{ + C}}{{\bf{l}}_{\bf{2}}}\left( {\bf{s}} \right)\)

Step 3:Reasons to keep them separate

Both the elements are very reactive and separated by molten \({\rm{NaCl}}\)and iron screens duringproduction to prevent recombination. 

Chlorine gas goes to storage tanks, and sodium (less dense than molten \({\rm{NaCl}}\)) floats to the surface into a collector.When an electric current passes through molten sodium chloride, it decomposes into sodium metal and chlorine gas. 

To prevent the spontaneous formation of sodium chloride, the products must be kept separate.