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OCR for page 42
42 Name: SODIUM CARBONATE, SODA ASH CAS No.: 497 - 19 - 8 Chemical Formula: Na2CO3 Description: NAS/CWTC 018 - 82 Formula Weight: 105. 0 Sodium carbonate, anhydrous is a white granular material The alkali equivalent of 100% sodium carbonate is 58.48% sodium oxide. Use: Used for pH adjustment. Purity Requirements: .. The RMIC values are based on a maximum dosage of 100 me of sodium carbonate/liter of water and are to be compared to impurity concentrations obtained by using sample proce- dures described in this monograph. If the actual dosage is other than 100 mg/liter, the user is cautioned to con- sult Table 2 for appropriate RMIC values. Impurity Chromium Lead Bulk Sample Collection: RMIC mg ImpuritY/kg Sodium Carbonate - 50 50 Sample in accordance with Standard for Soda Ash, AWWA B201-80, American Water Works Association, Denver, Colorado (1980).

OCR for page 42
43 Analytical Sample Preparation: Weigh out 2.5 g of sodium carbonate. In a 150-ml acid- washed beaker, dissolve the sample with 100 ml of deionized distilled water. Under a hood, acidify the solution with concentrated HC1 to a pH of less than 2. Add hydroxylamine hydrochloride until the solution turns clear. Gently heat the solution to reduce the volume below 100 ml, making certain that it does not boil. Quan- titively transfer to a 100-ml acid-washed volumetric flask and make to volume with deionized distilled water. Process a reagent blank by the same procedure. Sample Analyses _: The analyses are to be performed on the sodium carbonate solution in accordance with: Standard Methods for the Examination of Water and Waste- water, 15th Edition, American Public Health Association, Washington, D.C. (1981). Chromium Lead Section 304 Section 304