Solvents
In a solution, a solvent is the substance which comprises the bulk of the solution. The substance that is dissolved into the solvent is the solute. A solvent is a substance capable of dissolving another substance. If some of the components of this system chemically react with each other then the inert substance dispersing the reactants is the inert solvent.
One of the most commonly encountered solvents is water. Water is an excellent solvent for many ionic substances but not for the majority of organic substances. Because water is a polar molecule, the water molecules can easily break down ionic crystals and separate the component ions from each other. The water molecules then form a shell around the ions keeping them further apart. Organic compounds and other covalently bonded molecules do not dissolve well in water. One exception to this is some of the alcohols. Because of the hydrogen bonding that is possible, some alcohols will dissolve in water.
A solvent other than water is required for other organic chemicals. Organic solvents (non-aqueous solvents) are capable of dissolving covalent compounds that are not ionic. An example of an organic solvent is cyclohexane.Iodine is virtually insoluble in water but it will readily dissolve in cyclohexane. Organic solvents are used in a variety of commonly encountered substances including correction fluid, glue, paint, varnish, and aerosols. Some of these organic solvents are flammable and can potentially form explosive mixtures with air. It is for these reasons that aerosols and other devices containing organic solvents need to be used carefully and in locations with good ventilation.
It is important to realize that the solvent does not need be a liquid and the solute does not need to be a solid. Solutions can be formed in which a gas is dissolved in another gas, or in a liquid or a solid. Solid-solid and liquid-liquid solutions are also common.
The temperature of the solvent will control how much solute can dissolve in it. In most cases, the higher the temperature the more solute will dissolve in the solvent. One exception to this is when a gas dissolves in water. The solubility of a gas in liquid typically decreases with temperature.
With some solvents a chemical reaction occurs with the solute. This means that more of the solute will apparently dissolve in the solvent, but the original solute will not be recoverable by evaporation.
The physical properties of a solvent are altered once a solute has been added. Exactly how these properties are affected depends upon the solvent-solute combination in use. For example, when solutes are added to water the freezing point is lowered and the boiling point is raised.
A solvent is a substance (solid, liquid, or gas) that is capable of dissolving another substance to produce a solution.
This is the complete article, containing 456 words
(approx. 2 pages at 300 words per page).
