gravimetry - 12/14/2011 Gravimetric Method of Analysis...

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12/14/2011 1 Principles of Gravimetric Analysis Jonyl L. Garcia , R.Chem., MSc. Chem. ( Cand. ) Chemistry Department Adamson University Ermita, Manila 12/14/2011 5:33 PM 1 Analytical Chemistry 2 (Chem) Gravimetric Method of Analysis Quantitative method in which he mass of a pure compound (product) is used to determine the quantity of the analyte from the original sample. The oldest analytical technique, one of the most accurate and precise macroanalytical technique. 12/14/2011 5:33 PM Analytical Chemistry 2 (Chem) 2 Types of Gravimetric Methods Precipitation Gravimetry The analyte is separated from a solution of the sample as a precipitate and is converted to a compound of known composition that can be weighed Example: Analysis of KCl sample by precipitation to AgCl 12/14/2011 5:33 PM Analytical Chemistry 2 (Chem) 3 Types of Gravimetric Methods Volatilization Gravimetry The analyte is separated from other constituents of a sample by conversion to a gas of known composition. The weight of the gas serves as a measure of analyte concentration. Example: Determination of NaHCO 3 by decomposing the sample with strong acid to convert the analyte into CO 2 (g) and water. The gas is then weighed. 12/14/2011 5:33 PM Analytical Chemistry 2 (Chem) 4 Types of Gravimetric Methods Electrogravimetry The analyte is separated by deposition on an electrode by an electrical current. The mass of the product then provides a measure of the analyte concentration. Example: Analysis of Cu by electrodeposition method 12/14/2011 5:33 PM Analytical Chemistry 2 (Chem) 5 Types of Gravimetric Methods Particulate Gravimetry Involves the determination of a particulate analyte’s mass following its separation from the sample matrix Example: Determination of total suspended solids by filtering a liquid sample through a pre-weighed filtering material. 12/14/2011 5:33 PM Analytical Chemistry 2 (Chem) 6
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12/14/2011 2 PRECIPITATION METHODS 12/14/2011 5:33 PM Analytical Chemistry 2 (Chem) 7 Precipitation Gravimetry Analyte is converted to a sparingly soluble precipitate by addition of a precipitating agent. The precipitate is then filtered, washed free from impurities, converted to a product of known composition by suitable heat treatment, and weighed. 12/14/2011 5:33 PM
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This note was uploaded on 02/02/2012 for the course CHEM 211 taught by Professor Santos,j during the Spring '11 term at Abu Dhabi University.

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gravimetry - 12/14/2011 Gravimetric Method of Analysis...

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