Salt analysis for Class 11–12 Chemistry: tests and virtual labs

Salt analysis (qualitative analysis) means finding which acid radical (anion) and which basic radical (cation) an unknown salt contains. Here are 17 virtual labs for the anion tests, the cation group tests and the flame test, so you can practise every step before the practical exam.

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What is salt analysis?

A salt is made of a positive ion (cation, the basic radical) and a negative ion (anion, the acid radical). In the Class 12 chemistry practical you get one unknown salt and must name both ions from simple tests: colour and smell, solubility, the flame test, and chemical tests in the test tube.

The usual order is: preliminary tests (colour, flame test, dilute acid test) first, then the tests for the anion, then the systematic separation of the cation into groups, and finally a confirmatory test for each ion you suspect.

Anion (acid radical) tests

Anions are grouped by the acid that gives them away. Carbonate, sulphide, sulphite, nitrite and acetate react with dilute sulphuric acid. Chloride, bromide, iodide and nitrate need concentrated sulphuric acid. Sulphate and phosphate are tested independently, for example sulphate with barium chloride and the brown ring test for nitrate.

Cation (basic radical) groups

Cations are separated into groups by adding one group reagent after another. Zero group is ammonium. Group I (lead) is precipitated as chlorides with dilute HCl. Group II (copper and lead) gives sulphides with H₂S in acid. Group III (iron, aluminium) is precipitated as hydroxides with NH₄Cl and NH₄OH. Group IV (cobalt, nickel, manganese, zinc) gives sulphides in a basic medium. Group V (calcium, strontium, barium) is precipitated as carbonates, and magnesium is group VI.

Always follow the order of the groups: a later group reagent is added only after the earlier group is removed.

Virtual labs: salt analysis (17)

Flame tests for metal ions Class 11 · free
Identify metal ions from the colour they give to a non-luminous flame.
Ammonia from an ammonium salt Class 11
Liberate ammonia from ammonium chloride with alkali and identify it.
Test for acetate ion Class 12
Identify acetate by the vinegar smell with dilute H₂SO₄ and the red colour with neutral FeCl₃.
Test for carbonate ion Class 12 · free
Identify carbonate by effervescence with dilute acid and the lime water test.
Brown ring test: nitrate and nitrite Class 12
Confirm nitrate with the brown ring test and distinguish it from nitrite.
Test for phosphate ion Class 12
Identify phosphate with ammonium molybdate (canary-yellow precipitate) and magnesia mixture.
Test for sulphate ion Class 12
Identify sulphate with barium chloride; the precipitate does not dissolve in conc. HCl. Confirm with lead acetate.
Test for sulphide ion Class 12
Identify sulphide by H₂S gas (lead acetate paper) and the sodium nitroprusside test.
Tests for aluminium and zinc ions Class 12
Identify Al³⁺ (white gelatinous hydroxide, soluble in excess NaOH) and Zn²⁺ (white ZnS, white ferrocyanide).
Test for ammonium ion (zero group) Class 12
Identify NH₄⁺ by ammonia evolved with NaOH and by Nessler's reagent.
Test for copper ion (group II) Class 12
Identify Cu²⁺: black CuS with H₂S (Na₂S), deep blue with excess ammonia, chocolate-brown with K₄[Fe(CN)₆].
Calcium, strontium and barium (group V) Class 12
Precipitate group V carbonates with ammonium carbonate and identify each ion by a specific test and its flame colour.
Test for iron(III) ion (group III) Class 12
Identify Fe³⁺: reddish-brown precipitate with NH₄OH/NH₄Cl, Prussian blue with ferrocyanide, blood red with thiocyanate.
Test for lead ion (group I) Class 12
Precipitate PbCl₂ with dilute HCl, dissolve it in hot water and confirm Pb²⁺ with KI and K₂CrO₄.
Test for magnesium ion (group VI) Class 12
Identify Mg²⁺ with disodium hydrogenphosphate in ammoniacal solution.
Tests for nickel and cobalt ions (group IV) Class 12
Both give black sulphides; distinguish Ni²⁺ (red with DMG) from Co²⁺ (blue with conc. HCl).
Group I cations: separating Pb²⁺ from Ag⁺ as chlorides Class 12
Precipitate Pb²⁺ and Ag⁺ with dilute HCl and tell the two white chlorides apart by hot water and ammonia.

Frequently asked questions

What is salt analysis in chemistry?

Salt analysis is the qualitative identification of the anion (acid radical) and the cation (basic radical) present in an unknown salt, using colour, solubility, the flame test and chemical tests.

How do I do salt analysis step by step?

Note the colour and smell, do the flame test, test the anion with dilute then concentrated sulphuric acid, and test the cation by passing through the group reagents in order (zero group, then groups I to VI). Confirm each ion with a specific test.

Can I practise salt analysis online?

Yes. Each test is a 3D virtual lab where you add the reagents and see the colour change, gas or precipitate. A number of labs are free.

Is salt analysis in the Class 12 chemistry practical?

Yes, the Class 12 chemistry practical includes the qualitative analysis of simple salts. Your teacher or board lists the exact ions you must know.

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