OCR Chem Higher - Soluble salt tests?!!!! Watch

john..........
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Report Thread starter 12 years ago
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:confused:

Can someone answer this question please?

The bottles of five colourless solutions have lost their labels.

They are known to contain the following sodium compounds.

sodium carbonate

sodium .chloride

sodium iodide

sodium nitrate

sodium sulphate

Veena does three tests on separate samples of each to work out their identities.

The tests and Veena's results are shown in the table.


Each unknown substance is represented by a letter A, B, C, D or E.

Use the information in the table to work out the identity of each solution.

A is sodium.......................... ..

8 is sodium.......................... ..

C is sodium.......................... ..

D is sodium.......................... ..

E is sodium.......................... ..

add 1 cm3 of dilute hydrochloric acid:
A - Nothing happens, B-Nothing happens C-Nothing happens D-Nothing happens E-Solution fizzes.

add 1 cm3 of dilute hydrochloric acid followed by 1 cm3 of barium chloride solution
A-white precipitate B-no precipitate C-no precipitate D-no precipitate E-no precipitate.

add 1 cm3 of dilute nitric acid followed by 1 cm3 of silver nitrate solution
A-no precipitate B-white precipitate C-yellow precipitate D-no precipitate E-no precipitate.
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AliciaK
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Report 12 years ago
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This is basically a test for ions question.

Acid + carbonate --> salt + water + carbon dioxide (with fizzing)
so E is sodium carbonate

If you add HCl then BaCl2 to a solution containing sulphate ions, a white precipitate of BaSO4 is formed, so A is sodium sulphate.

Finally, if you add dilute nitric acid and then silver nitrate solution to a solution containing Cl- you get a white precipitate, if you add them to a solution containing I- you get a yellow precipitate (and for Br- you get cream, but that's not used here).
So B is sodium chloride and C is sodium iodide.

And all that's left is D, which must be sodium nitrate.
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john..........
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Report Thread starter 12 years ago
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great thanks.
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