write the procedure for prepartion of standard solution for limit test for heavy metal
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a heavy metal is done trough a deep process metalls like iron has to have a definite galvanisation cause pure iron is dangerous
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A heavy metal is done trough a deep process metalls like iron has to have a definite galvanisation cause pure iron is dangerous.
- Moisten the residue with 1 drop of hydrochloric acid, add 10 ml of hot water and digest for 2 minutes.
- Add ammonia solution dropwise until the solution is just alkaline to litmus paper, dilute to 25 ml with water and adjust with dilute acetic acid to a pH between 3.0 and 4.0.
What is standard solution in limit test?
- Limit test of chloride is based on the reaction of soluble chloride with silver nitrate in presence of dilute nitric acid to form silver chloride, which appears as solid particles (Opalescence) in the solution.
- Observation: The opalescence produce in sample solution should not be greater than standard solution.
How do you prepare a standard iron solution for a limit test?
Chemicals Required:
- Standard Iron solution Ferric ammonium sulphate (1.726 g) dissolved in 10 ml of 0.1 N H₂SO4 and sufficient water to produce 1000 ml.
- Sulphuric acid (0. 1 N): 10.0 ml.
- Iron-free citric acid solution (20% w/v): 2.0 ml.
- Thioglycolic acid: 0.1 ml.
- Iron-free ammonia solution: 20 ml.
What do you mean by standard solution?
- A standard solution is a a solution of accurately known concentration prepared from a primary standard (a compound which is stable, of high purity, highly soluble in water and of a high molar mass to allow for accurate weighing) that is weighed accurately and made up to a fixed volume.
Learn more about standard solution here,
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