why HCl is added in limit test for sulphate?
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Answer:
Hydrochloric acid helps to make solution acidic and the barium sulphate precipitate formed is insoluble which gives turbidity. 17. Compare the turbidity produced in the test solution with the standard turbid solution.
The sample solution's turbidity should not exceed that of the standard solution. Hydrochloric acid aids in the acidification of a solution. Alcohol aids in the prevention of oversaturation. Potassium sulphate is employed to boost the sensitivity of the test increasing the ionic concentration in the reagent. The precipitation process is used in the chloride limit test. When soluble chloride combines with silver nitrate in the presence of dilute nitric acid to produce silver chloride, which appears in the solution as solid particles, chloride precipitates occur (opalescence).