Hardness Of Natural Waters example essay topic

Properties Water (h 2 0) is a liquid at room temperature, is odorless, tasteless, has a blush tint which may be detected; however, only in layers of significant depth. The freezing point of water is 0 degrees Celsius (32 degrees Fahrenheit), and its boiling point is 100 degrees Celsius (212 degrees Fahrenheit). Water attains its maximum density at a temperature of 4 degrees Celsius (39 degrees Fahrenheit) and expands upon freezing. Water is one of the best known ionizing agents. Because most substances are somewhat soluble in water, it is frequently stated as the universal solvent.

Water combines with certain salts to form hydrates. Water also reacts with metal oxides to form acids. It acts as a catalyst in many important chemical reactions. Occurrence Water is the only substance now known to man, that can occur at ordinary temperatures in all three states of matter, that is, as a solid, a liquid, and as a gas. As a solid, or ice, it is found as glaciers, and ice caps, on water surfaces in winter, as snow, hail and frost, and as clouds formed of ice crystals. Water occurs in the liquid state as rain clouds formed of water droplets, and on vegetation, or otherwise dew; in addition it covers three covers of the surface of the earth in the form of swamps, lakes, rivers, streams, ponds, oceans, etc.

As a gas, or in other words water vapor. It occurs as fog, steam, and clouds. Atmospheric vapor is measured in terms of relative humidity, which is the ratio of the quantity of vapor actually present to the greatest amount possible at a given temperature. Life and Water Water is a major constituent of living matter. From 50 to 90 percent of the weight of living organisms is water. Protoplasm, the basis materia of living cells, consists of a solution in water of fats, carbohydrates, proteins, salts, and similar chemicals.

Water acts as a solvent, carrying, joining, and chemically breaking down these substances. The Purification of Water Hanging and dissolved impurities present in naturally occurring water make it unsuitable for many purposes. Objectionable organic and inorganic materials are removed by such methods as screening and sedimentation to eliminate suspended materials; treatment with such compounds as activated carbon to remove taste and odors; filtration; and chlorination or irradiation to kill ineffective microorganisms. In aeration, or the saturation of water with air in such a manner as to produce greatest diffusion, usually by spraying water into the air in fountains. Aeration removes odors and taste caused by decomposing organic matter, and also industrial waste such as phenols and volatile gases such as chlorine. It also converts dissolved iron and manganese compounds into insoluble hydrated oxides of the metals which may then be readily settled out.

Hardness of natural waters is caused largely by calcium and magnesium salts and to a small extent by iron, aluminum, and other metals. Hardness resulting from the bicarbonates and carbonates of calcium and magnesium is called temporary hardness and can be removed by boiling, which also sterilizes the water. The residual hardness is known as noncarbonate, or permanent, hardness. The methods of softening noncarbonate hardness include the addition of sodium carbonate and lime and filtration through natural or artificial zeolites which absorb the hardness-producing metallic ions and release sodium ions to the water. Sequestering agents in detergents serve to inactivate the substances that make water hard. Iron, which causes a bad taste in drinking water, may be removed by aeration and sedimentation or by passing the water through iron-removing zeolite filters, or the iron may be stabilized by addition of such salts as poly phosphates.

For use in laboratory applications, water is either distilled or demineralize d by passing it through ion-absorbing compounds. THE EXITING WORLD OF WATER.