Why must the silver nitrate test for chloride ions be done in an acidified solution?

Answer 1

Because silver, like most of the heavier metals, forms an insoluble hydroxide.

In order to determine the presence of the halide, competing equilibria must be taken into account. Silver forms an insoluble hydroxide, which is probably a hydrous oxide. When #pH# is lowered from #7#, this competing equilibrium is removed, any chloride will precipitate as a curdy white solid as #AgCl#, as a lemon-yellow solid as #AgBr#, and as a bright yellow solid as #AgI#.

The acid of choice would be #HNO_3(aq)#. Why do we use this acid and not say #HCl(aq)# or #HBr(aq)#?

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Answer 2

Serenity Allen

The silver nitrate test for chloride ions must be done in an acidified solution to prevent the precipitation of other ions that may interfere with the test and to ensure that the silver ions remain in solution to react specifically with the chloride ions.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.