Presentation on theme: "Chlorine Dorothy Li (26) Stephanie Lowe (27) Michelle Mang (28) Nancy Mui (29)"— Presentation transcript:
Chlorine Dorothy Li (26) Stephanie Lowe (27) Michelle Mang (28) Nancy Mui (29)
What is Chlorine Chlorine is a greenish yellow gas which combines directly with nearly all elements. Chlorine is a respiratory irritant. The gas irritates the mucous membranes and the liquid burns the skin. As little as 3.5 ppm can be detected as an odour, and 1000 ppm is likely to be fatal after a few deep breaths. It was used as a war gas in 1915. It is not found in a free state in nature, but is found commonly as NaCl (solid or seawater). Here is a photo showing chlorine:
It is rarely necessary to make chlorine in the laboratory as it is readily available commercially in cylinders. Chlorine is found largely in seawater where it exists as sodium chloride. It is recovered as a reactive, corrosive, pale green chlorine gas from brine (a solution of sodium chloride in water) by electrolyis. Electrolysis of molten salt, NaCl, also succeeds, in which case the other product is sodium metal rather than sodium hydroxide.
What is the use of Chlorine Chlorine is also used widely in the manufacture of many everyday items. It is used to kill bacteria and other microbes from drinking water supplies. Even small water supplies are now routinely chlorinated. It is also used widely in paper product production, antiseptic, dyestuffs, food, insecticides, paints, petroleum products, plastics, medicines, textiles, solvents, and many other consumer products. Chlorine is also an important chemical in water purification, in disinfectants in bleach and in mustard gas.
The health effects of chlorine Chlorine is a highly reactive gas. It is a naturally occurring element. The largest users of chlorine are companies that make ethylene dichloride and other chlorinated solvents, polyvinyl chloride resins, chlorofluorocarbons, and propylene oxide. Paper companies use chlorine to bleach paper. Water and wastewater treatment plants use chlorine to reduce water levels of microorganisms that can spread disease to humans (disinfections). Exposure to chlorine can occur in the workplace or in the environment following releases to air, water, or land. People who use laundry bleach and swimming pool chemicals containing chlorine products are usually not exposed to chlorine itself. Chlorine is generally found only in industrial settings. Chlorine enters the body breathed in with contaminated air or when consumed with contaminated food or water. It does not remain in the body, due to its reactivity.
Effects of chlorine on human health depend on how the amount of chlorine that is present, and the length and frequency of exposure. Effects also depend on the health of a person or condition of the environment when exposure occurs. Breathing small amounts of chlorine for short periods of time adversely affects the human respiratory system. Effects differ from coughing and chest pain, to water retention in the lungs. Chlorine irritates the skin, the eyes, and the respiratory system. These effects are not likely to occur at levels of chlorine that are normally found in the environment. Human health effects associated with breathing or otherwise consuming small amounts of chlorine over long periods of time are not known. Some studies show that workers develop adverse effects from repeat inhalation exposure to chlorine, but others will not.
Environmental effects of chlorine Chlorine dissolves when mixed with water. It can also escape from water and enter air under certain conditions. Most direct releases of chlorine to the environment are to air and to surface water. Once in air or in water, chlorine reacts with other chemicals. It combines with inorganic material in water to form chloride salts, and with organic material in water to form chlorinated organic chemicals. Because of its reactivity chlorine is not likely to move through the ground and enter groundwater. Plants and animals are not likely to store chlorine. However, laboratory studies show that repeat exposure to chlorine in air can affect the immune system, the blood, the heart, and the respiratory system of animals. Chlorine causes environmental harm at low levels. Chlorine is especially harmful to organisms living in water and in soil.