Question

Which one of the following electrolytes is used in Down’s process of extracting sodium metal?
A.$NaCl + KCl + KF$
B.$NaCl$
C.$NaOH + KCl + KF$
D.$NaCl + NaOH$

Answer 1

Hint:To answer this question, you must recall the methods used in the extraction of various metals. Down’s process is an electrochemical extraction method used for the preparation of sodium metal.

Complete answer:
Down’s process is an extraction process based on the principle of electrolysis. It is a commonly used metal for the extraction of metallic sodium on industrial scale. It involves the electrolysis of molten sodium chloride.
The reaction taking place at the anode during the process is $2C{l^ - } \to C{l_2} + 2{e^ - }$
The reaction taking place at the cathode during the process is $2N{a^ + } + 2{e^ - } \to 2Na$
The overall cell reaction is given as $2N{a^ + } + 2C{l^ - } \to 2Na + C{l_2}$
In addition to this, the reaction faces some complexities because sodium chloride is an ionic compound and has a very high melting point. It melts at a temperature of around $1074{\text{K}}$which is very difficult to attain. As a result, potassium chloride and potassium fluoride are added in order to decrease the melting point. They also increase the electrical conductivity of the electrolytic process thus, making it more feasible.

Thus, the correct answer is A.

Note:
The process of electrolysis is carried out in a large rectangular steel container which is known as the Down’s cell. For anode, a graphite rod is used which is present at the center of the cell. The cathode is made up of iron and it surrounds the graphite anode. In between a round hollow wire gauge partition is inserted, so as to keep the electrodes isolated from each other and avoid the mixing of the products so formed. When electricity is passed at high voltage, the electrolysis of the sodium chloride takes place which gives metallic sodium and chlorine gas.