Question

Which one of the following statements is correct for precipitation method?

(a) Growth of the crystal from a solvent of same composition to the crystals

(b) Growth of the crystal from the solute of same composition to the crystal

(c) Growth of the crystal from the gaseous species of different composition to the crystal

(d) Growth of the crystal from a solvent of different composition to the crystals.

I had been asked this question in a national level competition.

My question is taken from Growth of Single Crystals topic in chapter Preparative Methods of Solid State Chemistry

Answer 1

Correct answer is (d) Growth of the crystal from a solvent of different composition to the crystals.

To explain I would say: In contrast to the methods like zone melting, Stockbarger etc method in which melts solidify to get crystals that have the same composition as the melt, precipitation methods involves the growth of the crystals from a solvent of different composition to the crystals. The solvent may be one of the constituents of the desired crystal example, crystallization of salt hydrate crystals using water as the solvent.