Question

“The Castner's process is the process used for extraction of sodium in solid state.” Answer whether the above statement is true or false. If true enter 1, else 0.

Answer 1

Hint: Castner process is used for manufacturing sodium metal at high temperatures. The process has anode and cathode of nickel and iron respectively. At lower temperatures, the molten form solidifies and at higher temperatures it starts to melt.

Complete step by step answer:
Castner process is a process of manufacturing sodium metal from its hydroxide at high temperatures i.e., 330-degree Celsius. In this process nickel acts as an anode and iron acts as cathode. Below this temperature, the metal will solidify whereas the metal will start to dissolve in the molten form if the temperature is above 330-degree Celsius.
This process uses a ceramic crucible with a steel cylinder suspended in it. Both cathode and anode are situated inside this cylinder. The temperature at the bottom is made cooler and at the top it is hotter so that the sodium hydroxide remains solid in the neck and liquid in the body of the vessel.
Sodium metal forms at the cathode but fused sodium hydroxide electrolyte is denser than sodium. Wire gauze confines the sodium metal in order to accumulate at the top of the collection container. We can write the chemical equations for the reactions taking place at cathode and anode.
The reaction on cathode is:
 \[2N{a^ + } + 2{e^ - } \to 2Na\]
The reaction on anode is:
 \[2O{H^ - } \to \dfrac{1}{2}{O_2} + {H_2}O + 2{e^ - }\]
Although the temperature is high, yet some of the water produced remains dissolved in the electrolyte. This water diffuses in the electrolyte and leads to reverse reaction on the electrolyzed sodium metal. Hydrogen gas also accumulates and thus the efficiency of the process decreases.
 \[Na + {H_2}O \to \dfrac{1}{2}{H_2} + N{a^ + } + O{H^ - }\]

Hence, it is true that “The Castner's process is the process used for extraction of sodium in solid state.” We can state it as 1.

Note:
One should not confuse himself with the Castner-Kellner process. This process is a method of electrolysis of an aqueous alkali chloride solution to produce the respective alkali hydroxide. The best example is sodium chloride solution which is also called brine.