Question

What is the Principle of Limit Test for Chloride?

Answer 1

Limit test: The litmus test is used for the estimation of chloride ions.

• It is based on the principle that when Silver Nitrate(${\mathrm{AgNO}}_3$) and soluble Chloride form Silver Chloride($\mathrm{AgCl}$) which is insoluble in dilute Nitric Acid(${\mathrm{HNO}}_3$).
• It makes the test solution turbid and the extent of turbidity depends upon the amount of chloride present in the substance.
• The formation of Silver Chloride appears as solid particles in the solution.

$\underset{\mathrm{Chloride}\mathrm{ion}}{{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right)}+\underset{\mathrm{Silver}\mathrm{nitrate}}{{\mathrm{AgNO}}_3\left(\mathrm{aq}\right)}\stackrel{{\mathrm{HNO}}_3}{\to }\underset{\mathrm{Silver}\mathrm{chloride}}{\mathrm{AgCl}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitrate}\mathrm{ion}}{{{\mathrm{NO}}_3}^{-}\left(\mathrm{aq}\right)}$