Water Quality Testing An experiment for CHEM 1212K. Introduction Water and Analytical Chemistry The use of analytical chemistry to determine the concentrations of certain substances in water is an important aspect of municipal and industrial water management. In wastewater treatment plants, analysis of the water exiting the plant provides end―-of-pipe? metrics that verify the safety of the water for human consumption. Analytical testing of environmental water can reveal problematic contamination of natural lakes, rivers, or streams. Industrial companies that use large amounts of water depend on measures of water quality to ensure that their products are safe and consistent. Whether in a natural or man-made environment, analytical water testing often relies on the conversion of aqueous species to known forms that are easily measured, such as colored compounds or solids. Each analytical method involves a particular chemical transformation that is specific for the species of interest and quantitative (i.e., the species is converted completely to a measurable form). Although these ideals can never be achieved in practice, they provide a standard to which all quantitative analytical chemists should aspire. In this experiment, we will study some components of municipal and natural water, neither of which are strictly considered pollutants. It is important to appreciate that the impact of pollutants on environmental water can be complex and indirect. In the early days of pollution control, environmental chemists focused on concentration as the major determinant of toxicity. Pollutant concentrations were measured directly and efforts centered on lowering the concentrations of pollutants in municipal water to minimally toxic levels. More recently, it has become clear that some pollutants can cause harm indirectly by decreasing the concentrations of beneficial dissolved species. For example, dumping of organic material into a natural water system can cause an increase in amounts of bacteria and algae in the water. These microorganisms in turn deplete dissolved oxygen in the water, harming fish and other aquatic wildlife that depend on the dissolved oxygen for respiration. In this context, climate change represents an important non-traditional pollutant, as temperature affects the concentration of dissolved oxygen as well. Some minerals dissolved in water provide demonstrated health benefits. Calcium and magnesium ions that contribute to water hardness are two important examples. These ions are often introduced to environmental water sources through natural rather than industrial means; for example, hard water containing high calcium concentrations may be found in streams or springs passing over limestone (calcium carbonate). Hardness has an important cosmetic impact on water quality in that dissolved calcium and magnesium affect the taste of the water itself and the perception of other flavor compounds in beverages made from the water.