YESENIA MONTAÑA MURCIA
UNIVERSITY OF TOLIMA
DISTANCE EDUCATION INSTITUTE
NEVA – HUILA
A solvent (from the Latin solvere, "loosen") is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent ata specified temperature. Common uses for organic solvents are in dry cleaning (e.g. tetrachloroethylene), as a paint thinner (e.g. toluene, turpentine), as nail polish removers and glue solvents (acetone, methyl acetate, ethyl acetate), in spot removers (e.g. hexane, petrol ether), in detergents (citrus terpenes), in perfumes (ethanol), and nail polish, (part of how it stays on nails) and inchemical synthesis. The use of inorganic solvents (other than water) is typically limited to research chemistry and some technological processes.
SOLUTIONS AND SOLVATION
When one substance is dissolved into another, a solution is formed. This is opposed to the situation when the compounds are insoluble and one of them precipitate like sandin water. In solution all of the ingredients are uniformly distributed. No residue is left in the bottom. The mixing is referred to as miscibility, whereas the ability to dissolve one compound into another is known as solubility. However, in addition to mixing, both substances in the solution interact with each other. When something is dissolved, molecules of the solvent arrange themselves aroundmolecules of the solute. Heat is involved and entropy is increased making the solution more thermodynamically stable than the solute alone. This arrangement is mediated by the respective chemical properties of the solvent and solute, such as hydrogen bonding, dipole moment and polarizability.
Solvents can be broadly classified into two categories: polar and non-polar.Generally, the dielectric constant of the solvent provides a rough measure of a solvent's polarity. The strong polarity of water is indicated, at 20 °C, by a dielectric constant of 80.10;. Solvents with a dielectric constant of less than 15 are generally considered to be nonpolar. Technically, the dielectric constant measures the solvent's ability to reduce the field strength ofthe electric field surrounding a charged particle immersed in it. This reduction is then compared to the field strength of the charged particle in a vacuum. In laymen's terms, dielectric constant of a solvent can be thought of as its ability to reduce the solute's internal charge.
* OTHER POLARITY SCALES
Dielectric constants are not the only measure of polarity. Because solvents are used bychemists to carry out chemical reactions or observe chemical and biological phenomena, more specific measures of polarity are required.
The polarity, dipole moment, polarizability and hydrogen bonding of a solvent determines what type of compounds it is able to dissolve and with what other solvents or liquid compounds it is miscible. As a rule of thumb, polar solvents dissolve polar compounds bestand non-polar solvents dissolve non-polar compounds best: "like dissolves like". Strongly polar compounds like sugars (e.g. sucrose) or ionic compounds, like inorganic salts (e.g. table salt) dissolve only in very polar solvents like water, while strongly non-polar compounds like oils or waxes dissolve only in very non-polar organic solvents like hexane. Similarly, water and hexane (or vinegarand vegetable oil) are not miscible with each other and will quickly separate into two layers even after being shaken well.
* POLAR PROTIC AND POLAR APROTIC
Solvents with a relative static permittivity greater than 15 can be further divided into protic and aprotic. Protic solvents solvate anions (negatively charged solutes) strongly via hydrogen bonding. Water is a protic solvent. Aprotic...