Question

In Down's process, a small amount of $KCl$ is added to $NaCl$:

• A. to decrease the melting point of $NaCl$
• B. to increase the electrical conductivity
• C. to maintain electrical contact
• D. to prevent the oxidation of sodium metal formed

Answer 1

The correct option is A to decrease the melting point of $NaCl$

Sodium chloride melts at a very high temperature of about $1085$ K. So, a mixture containing sodium chloride, potassium chloride and potassium fluoride $(NaCl+KCl+KF)$ is used. This mixture melts at about $850-875$ K. So, a small amount of $KCl$ is added to $NaCl$ to decrease the melting point of $NaCl$.