Question

To heat a substance to a high temperature but without melting or fusing to drive off volatile matter or to cause oxidation or reduction?

1) Sublimation
2) Evaporation
3) Distillation
4) Calcination

Answer 1

Calcination refers to heating a substance to a high temperature without melting for processes like driving off volatiles, or enabling oxidation or reduction, while sublimation is the direct solid-to-gas phase change requiring heat of sublimation.

Step-by-step explanation:

The process of heating a substance to a high temperature without melting or fusing it in order to drive off volatile matter, or to enable oxidation or reduction, is known as calcination. This is distinct from sublimation, which is when a substance changes from a solid directly into a gas, bypassing the liquid phase. The heat of sublimation is the energy required for this phase change, and it is calculated by adding the heat of fusion and the heat of vaporization according to Hess's law. Example substances that undergo sublimation include dry ice (solid carbon dioxide), iodine, naphthalene, and 1,4-dichlorobenzene.