Fundamentals of ChemistryDOE-HDBK-1015/1-93CHEMICAL BONDINGRev. 0CH-01Page 33CombiningElementsThe Laws of Definite Proportions and Multiple Proportions and the related portions of atomictheory form the bases for most quantitative calculations involving chemical reactions. Applyingthe basic chemical laws to chemical bonding will help the reader to understand the probabilityand proportions involved in chemical reactions. Regardless of the type of bond (ionic, covalent,coordinate covalent, or metallic), specific amounts of one element will react with specificamounts of the element(s) with which it is combined.If two substances are placed together in a container, in any ratio, the result is a mixture. Whena teaspoon of sugar is added to a glass of water, it will slowly dissolve into the water anddisappear from view. As a result, the molecules of sugar are evenly distributed throughout thewater and become mixed with the water molecules. Because the sugar and water mixture isuniform throughout, it is said to be homogeneous. A homogeneous mixture of two or moresubstances is called asolution. The reason solutions are classified as mixtures rather than ascompounds is because the composition is not of fixed proportion.All solutions consist of a solvent and one or more solutes. The solvent is the material thatdissolves the other substance(s). It is the dissolving medium. In the water-sugar solution, thewater is the solvent. The substances that dissolve in the solution are called solutes. In thewater-sugar solution, sugar is the solute. It is not always easy to identify which is the solventand which is the solute (for example, a solution of half water and half alcohol).Solutions can exist in any of the three states of matter, solid, liquid, or gas. The earth'satmosphere is a gaseous solution of nitrogen, oxygen, and lesser amounts of other gases. Wine(water and alcohol) and beer (water, alcohol, and CO ) are examples of liquid solutions. Metal2alloys are solid solutions (14-karat gold is gold combined with silver or copper).One factor that determines the degree and/or rate at which a reaction takes place is solubility.Solubilityis defined as the maximum amount of a substance that can dissolve in a given amountof solvent at a specific temperature. At this point, the solution is said to be saturated. Asolution is saturated when equilibrium is established between the solute and the solvent at aparticular temperature. Equilibriumis the point at which the rates of the forward and reversereactions are exactly equal for a chemical reaction if the conditions of reaction are constant.Kinetics is the study of the factors which affect the rates of chemical reactions. There are fiveprinciple factors to consider: concentration, temperature, pressure, the nature of the reactants,and the catalyst.
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business