Miscibility

Submitted by ChemPRIME Staff on Thu, 12/16/2010 - 14:03


When a solidA state of matter having a specific shape and volume and in which the particles do not readily change their relative positions. dissolves in a liquidA state of matter in which the atomic-scale particles remain close together but are able to change their positions so that the matter takes the shape of its container, we very seldom find that the liquid has any tendency to dissolve in the solid. In a saturatedDescribes 1) a solution that contains the equilibrium concentration of a solute, or 2) an organic compound that contains no double or triple bonds (such as an alkane). solutionA mixture of one or more substances dissolved in a solvent to give a homogeneous mixture. of potassium chloride, for example, essentially no water dissolves in the potassium chloride crystals. With liquids the situation is usually different. If equal quantities of 1-butanol and water are shaken together, the mixtureA combination of two or more substances in which the substances retain their chemical identity. slowly separates into two layers. The bottom layer is a saturated solution of 1-butanol in water—it contains about 8% 1-butanol by weightA measure of the gravitational force on an object; directly proportional to mass.. The top layer is not pure 1-butanol but a saturated solution of water in 1-butanol. It contains about 32% water by weight. A pair of liquids, like 1-butanol and water, which separates into two layers is said to be partially miscibleWith respect to two liquids, able to dissolve in each other in any proportion..

By contrast with the solubilities of solids in liquids, a great many liquid pairs are completely miscible. That is, regardless of the proportions in which the two liquids are mixed, each will dissolve completely in the other. There will be no phase boundary as in the case of partially miscible liquids like 1-butanol and water. Ethanol and water provide a good example of two liquids which are completely miscible. If you have a source of pure ethanol, it is possible to mix a drink in any proportions you like-even up to 200 proof—without forming two separate liquid phases.