Question

Which of the following is most economically refined by fractional distillation?

• A. $\mathrm{Zn}$
• B. $\mathrm{Ni}$
• C. $\mathrm{Cu}$
• D. $\mathrm{Fe}$

Answer 1

The correct option is A

$\mathrm{Zn}$

The explanation for correct option:

(a) $\mathrm{Zn}$

1. Fractional distillation is the process of utilising distillation to separate a liquid mixture into fractions with different boiling points, usually using a fractionating column.
2. Repeated distillations and condensations are used in the process, and the mixture is usually divided into component parts.
3. The main impurities in Zn are generally cadmium, lead, and iron.
4. There is very less difference in the boiling point of zinc and these impurities so zinc can be refined using fractional distillation.
5. So, for refining the fractional distillation process is used.

The explanation for incorrect option:

(b) $\mathrm{Ni}$

1. For refining $\mathrm{Ni}$, vapor phase refining process is used.
2. The technique of refining metal by converting it to its volatile constituent and then decomposing it to get pure metal is known as vapor phase refining.
3. It is also known as Mond's process

(c) $\mathrm{Cu}$

1. For refining $\mathrm{Cu}$, an electrolytic process is used.
2. Electrolytic refining is the process of refining a metal (mainly copper) by the process of electrolysis.
3. When it comes to the mechanics of the process, a large chunk or slab of impure metal serves as the anode, while a thin strip of pure metal serves as the cathode.

(d) $\mathrm{Fe}$

1. For refining $\mathrm{Fe}$, oxidative refining is used.
2. Oxidative refining is used for refining metal in those cases in which the impurities have a greater tendency to get oxidized than the metal itself.

Therefore, Option (a) is correct, $\mathrm{Zn}$ is refined by fractional distillation.