Chem Report
Compleximetric Determination of Water Hardness
Caindec, Patricia Ysabel B.
Water hardness is a measure of the amount of calcium and magnesium carbonate dissolved as Ca 2+ and Mg 2+ in water. There are no health hazards associated with water hardness, however, it causes scaling, as well as forming of soap suds. Compleximetric titration is one of the best ways of measuring total water hardness using a standard ethylenediaminetetraacetic acid (EDTA) solution. EDTA solution is used as it has the ability to easily bind with calcium and magnesium ions. EDTA and Ca2+ react at the ratio of 1:1. The purpose of this experiment is to determine the hardness of water by measuring the concentrations of calcium and magnesium in water samples by titration. The total hardness is expressed in terms of the equivalent concentration of calcium carbonate in parts per million. The amount of CaCO3, in this experiment, is determined by titrating calcium ions from a sample tap water (from Baguio).
Water hardness is a commonly reported aspect of water quality. Hard water is water that contains high concentrations of Ca2+ and Mg2+ ions. Even with this concentration it is safe to drink and is apt for cooking and cleaning and is not a health hazard. Calcium carbonate (CaCO3) is a common substance found in rocks. It is usually the principal cause of hard water. Magnesium carbonate, MgCO3, is a white solid that occurs in nature as a mineral. Hardness is traditionally measured by chemical titration. The hardness of a water sample is reported in milligrams per liter or parts per million. In a compleximetric titration, a solution containing the free metal ion of interest is titrated with a solution of chelating agent until all of the metal ions are completely complexed. The endpoint is usually measured with an indicator ligand that forms a colored complex with the free metal ion. The most important chelating agent in analytical chemistry is
Caindec, Patricia Ysabel B.
Water hardness is a measure of the amount of calcium and magnesium carbonate dissolved as Ca 2+ and Mg 2+ in water. There are no health hazards associated with water hardness, however, it causes scaling, as well as forming of soap suds. Compleximetric titration is one of the best ways of measuring total water hardness using a standard ethylenediaminetetraacetic acid (EDTA) solution. EDTA solution is used as it has the ability to easily bind with calcium and magnesium ions. EDTA and Ca2+ react at the ratio of 1:1. The purpose of this experiment is to determine the hardness of water by measuring the concentrations of calcium and magnesium in water samples by titration. The total hardness is expressed in terms of the equivalent concentration of calcium carbonate in parts per million. The amount of CaCO3, in this experiment, is determined by titrating calcium ions from a sample tap water (from Baguio).
Water hardness is a commonly reported aspect of water quality. Hard water is water that contains high concentrations of Ca2+ and Mg2+ ions. Even with this concentration it is safe to drink and is apt for cooking and cleaning and is not a health hazard. Calcium carbonate (CaCO3) is a common substance found in rocks. It is usually the principal cause of hard water. Magnesium carbonate, MgCO3, is a white solid that occurs in nature as a mineral. Hardness is traditionally measured by chemical titration. The hardness of a water sample is reported in milligrams per liter or parts per million. In a compleximetric titration, a solution containing the free metal ion of interest is titrated with a solution of chelating agent until all of the metal ions are completely complexed. The endpoint is usually measured with an indicator ligand that forms a colored complex with the free metal ion. The most important chelating agent in analytical chemistry is
References: [1] http://mccord.cm.utexas.edu/courses/spring2005/ch455/Spr05455Wk4Lab.pdf [2] http://ph.answers.yahoo.com/question/index?qid=20100914060152AAxbo3I [3] http://en.wikipedia.org/wiki/EDTA [4]http://www.gannon.edu/resource/dept/sim/new/chemexp_files/Most%20used%20ChemLabs/PDF%20Files/pH%20water%20hardness.pdf