Test for Cations

There are two tests that can be carried out for cations (positively charged), using aqueous sodium hydroxide and aqueous ammonia.

Test for cations using aqueous sodium hydroxide

To an aqueous solution of the sample, add aqueous sodium hydroxide a little at a time (until a change is observed) until it is present in excess (no further change is observed)
Observe the colour of precipitate and the solubility of the precipiate in excess.
If there is no precipitate, warm the mixture and test for ammonia gas.

A diagram to illustrate the test for cations using sodium hydroxide is as follows:


cation_test_with_NaOH.jpg

Test for Cations using Aqueous Ammonia

To an aqueous solution of the sample, add aqueous ammonia a little at a time (until a change is observed) until it is present in excess (no further change is observed)
Observe the colour of precipitate and the solubility of the precipiate in excess.
A diagram to illustrate the test for cations using sodium hydroxide is as follows:


cation_test_with_NH3.jpg


Summary Table (Test for Cations)

table_for_cations_test.jpg


Test for Aluminium Ion:







Test for Calcium Ion:





Test for Iron (III) Ion:

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Test for Iron (II) Ion:




Test for Lead (II) Ion:






Test for Copper (II) Ion:



Test for Ammonium Ion:


Complete the Quiz on Cations in iLMS.