Today, I am going to show you all the tests that you should be expecting in this year’s exam. This is not a prediction, what I am here for is to let know how to carry out all tests on the sample the salt. So, I will encourage you to get your pen and paper and write down where necessary.
In this year’s exam , you are going to analyse copper (II) tetraoxosulphate (VI) salt and it will be tagged C. the following tests will carried out on the sample of copper(II) tetraoxosulphate (VI):
a. Solubility test
b. Test with sodium hydroxide
c. Test with aqueous ammonia solution
d. Test with barium chloride solution and dilute hydrochloric acid.
The table shows all the tests
S/n | Test | Observation | Inference |
1 | C + distilled water, stir and divide into three portions | Soluble and gives light blue solution | Soluble salt present and transition ions likely present |
2 | To the first portion, add dilute NaOH solution in drops then in excess | Pale blue gelatineous precipitate , insoluble in excess | Cu2+ present |
3 | To the second portion, add aqueous ammonia solution in drops then in excess | Light blue gelatineous precipitate,soluble in excess to give a deep blue solution | Cu2+ confirmed |
4 | To the third portion, add BaCl2 solution,
Then dilute HCl | White precipitate formed
Insoluble in dilute HCl | SO32-, SO42- or CO32- likely present.
SO42- confirmed |
Note: Barium chloride forms white insoluble compounds with trioxocarbonate (IV), trioxosulphate (IV) and tetraoxosulpate (VI) but the first two are soluble in HCl
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