What process involves removing impurities and increasing the concentration of a substance?

The process that involves removing impurities and increasing the concentration of a substance is distillation. Distillation is a method that relies on differences in boiling points to separate components of a mixture. When a liquid mixture is heated, the component with the lowest boiling point vaporizes first. The vapor is then cooled and condensed back into a liquid, resulting in a purified substance that is more concentrated than the original mixture.

In distillation, impurities that have higher boiling points are left behind, effectively increasing the purity and concentration of the desired component. This technique is commonly used in chemistry and various industries to purify liquids, such as in the production of distilled water or alcoholic beverages.

While other processes like filtration, purification, and separation could also involve removing impurities, they do not specifically refer to the method of increasing concentration through vaporization and condensation like distillation does.