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Wednesday, 10 September 2014

· Limit Test for Chlorides

 To 15ml of the prescribed solution add 1ml of dilute nitric acid R and pour the mixture as a single addition into a test-tube containing 1 ml of silver nitrate solution R2. Prepare a standard in the same manner using 10ml of chloride standard  solution (5 ppm Cl)R and 5 ml
of water  R. Examine the tubes laterally against a  black background.
 
 After standing for 5min protected from light, any opalescence in the test solution is  not more intense than that in the standard.
 

Reagent used
§  Dilute Nitric Acid: Dilute 20g of nitric acid to 100ml  with water. Contains about12.5% w/v of HNO3(about 2M).
§  Silver Nitrate Solution: A freshly prepared 5.0% w/v  solution of  silver nitrate .
§  Chloride Standard Solution (5 ppm Cl): Dilute 1volume of a 0.0824% w/v  solution of sodium chloride to 100 volumes with water  immediately before use.


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