Question

Which one of the following principle has been used in the zone melting method?

(a) Impurities concentrate in the solid than in liquid phase

(b) Impurities concentrate in the liquid phase than in gaseous phase

(c) Impurities concentrate in the liquid phase than in the solid phase

(d) Impurities concentrate in the gaseous phase than in the solid phase

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This question is from Growth of Single Crystals topic in section Preparative Methods of Solid State Chemistry

Answer 1

Right answer is (c) Impurities concentrate in the liquid phase than in the solid phase

To explain: Zone melting method make the use of the principle that impurities usually concentrate in the liquid rather than in the solid phase. Impurities are therefore ‘swept out’ of the crystal by the moving molten zone. The method has been used for the purification and crystal growth of the high melting metals such as tungsten.