CBSE Class 12 chemistry practical, Salt analysis · Salt analysis

Source: CBSE Class 12 chemistry practical syllabus · use your school laboratory manual (NCERT Lab Manual where your school uses it).

Salt analysis: cations (Class 12) (Class 12 chemistry practical)

You perform preliminary tests, prepare solution, and work through cation groups 0–VI as your manual orders.

This complements anion analysis — use the same unknown salt only in the school lab.

Published practice page. Concentrations, masses, and numerical answers come from your school laboratory manual and your own readings — not invented here. Not yet reviewed by a named chemistry reviewer. Version 1.0.0, updated 2026-10-03.

Safety — read before you start

Safety warning. Practise here. Perform the real experiment only in your school lab, with your teacher present.

H₂S extremely toxic.
Heavy metal ions toxic.
Ammonia and alkalis irritant.

Wear: Lab coat, Splash goggles, Gloves, as your teacher directs.

Follow your teacher’s disposal instructions. Do not pour leftovers down a household drain.

Loads only after you tap. Use the lab hands to pick up and use equipment (pointer hidden in the scene). Falls back to a flat diagram if WebGL is unavailable.

Aim

To identify the cation(s) present in the given inorganic salt by performing the group-wise analysis prescribed in your laboratory manual.

Methods and quantities can differ between schools. Follow your teacher's instructions.

Apparatus and chemicals

Apparatus and chemicals
Item	Note
Test tubes and rack	Group separations need many tubes.
Boiling water bath	For group precipitations.
Glass rod	Stir; do not mix rods between H₂S and lead tests.
Delivery tube (if H₂S generated)	Teacher-controlled H₂S source preferred.
Unknown salt (salt)	Issued by teacher.
Group reagents (group reagents)	Dilute HCl, H₂S (or thioacetamide), NH₄OH, (NH₄)₂CO₃, Na₂S, confirmatory reagents — manual only.
Flame test salts (optional) (flame)	Clean wire loop; compare flame colours cautiously.

Burette and conical flask set up for titration — Read the burette at eye level. The end-point colour in a diagram is only a guide — your titre is the volume you measure.

Theory and reaction

Open

Cations are classified into groups precipitated by specific reagents: e.g. Group I (Pb²⁺, Ag⁺, Hg₂²⁺) with dilute HCl; Group II with H₂S in acidic medium; Group III with NH₄OH/NH₄Cl; etc., as NCERT/CBSE scheme teaches.

Each group filtrate is tested for the next group after removing previous precipitate.

Confirmatory tests (specific colour, complex, or crystal test) must match group result.

Lead chloride precipitates in dilute HCl; solubility in hot water helps confirm lead.

Procedure

Preliminary: colour, flame test if manual includes, smell (only as teacher allows), dry heating.
Prepare aqueous solution or acid extract as manual directs. Note insoluble residue.
Group 0 / NH₄⁺ test if listed, then add group reagents in sequence. Separate precipitates and filtrates carefully.Safety: H₂S is extremely toxic — use teacher’s gas apparatus or thioacetamide method in ventilated area.
Within each positive group, run confirmatory tests for individual cations.
Write final cation report consistent with all group and confirmatory observations.

Observation table

Enter the readings from your school lab in the practical file below. This page does not fill them in for you.

Type the readings in your practical file

S. No.	Group / test (—)	Observation (—)	Cation inference (—)
1
2
3

Calculation

Qualitative identification — no numerical calculation.

Result

The cation(s) present in the given salt is/are ________ (write the ion(s) you confirmed).

Precautions

Follow group order strictly — skipping steps gives false groups.
H₂S and KCN (if ever mentioned in old texts) are deadly — school methods only.
Label filtrates; do not cross-contaminate test tubes.

Viva questions

Answer one question at a time. The full answers stay closed until you open them.

Question 1 of 4

Group II cations (acidic H₂S) include species like…

A. Pb²⁺ only in basic medium alwaysB. Cu²⁺, Hg²⁺, As³⁺ (as taught in manual scheme)C. Only Na⁺D. Only ammonium

Pick an answer first.

Show all questions and answers

Group II cations (acidic H₂S) include species like…
Answer: Cu²⁺, Hg²⁺, As³⁺ (as taught in manual scheme). Reason: Acidic H₂S precipitates Group II sulphides in the NCERT scheme.
NH₄Cl is added before NH₄OH in Group III mainly to…
Answer: Suppress OH⁻ concentration by common ion effect. Reason: NH₄⁺ lowers [OH⁻] so only Group III hydroxides precipitate at intended pH.
Flame test for Ca²⁺ may show…
Answer: Brick red (Sr similar — confirm further). Reason: Calcium gives brick red; strontium is similar — confirmatory tests distinguish.
Before group analysis, preparing a clear solution often requires…
Answer: Dissolving salt in water or dilute acid as manual. Reason: Soluble salts dissolve; carbonates may need acid to get ionic solution.

Common mistakes

Reporting Cu²⁺ from blue colour alone without group III/confirmatory tests.
Adding excess NH₄OH too early and redissolving needed precipitates.
Ignoring flame test when manual requires it for Group V/VI distinction.

Frequently asked questions

Can I do this at home?: No. Use this page to practise the order of steps and viva. Do the real experiment only in your school laboratory, with your teacher present.

Your practical file

Name, school, and roll number are optional and are not sent anywhere.

The practical file opens on this device.

Review

Not yet reviewed by a named chemistry reviewer. Published for practice only — follow your teacher and laboratory manual for quantities and safety.

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