Class 12 chemistry practicals (CBSE)

Prepare and compare lyophilic sols (e.g. starch or gum) with lyophobic sols (e.g. ferric hydroxide), and note how they differ in stability and dialysis behaviour.

Purify a prepared sol (often ferric hydroxide or starch) using a parchment or cellophane bag in distilled water and observe diffusion of electrolytes.

Shake oil and water to form an emulsion, then show how soap or gum stabilises the dispersion and how breaking agents act.

Study how concentration or temperature affects the time for a fixed amount of sulphur to turbid a marked cross beneath the flask.

Mix iodate, sulphite, and starch (or iodide–peroxide variant) and record the sudden blue-black appearance after a predictable induction time.

Dissolve a salt such as copper(II) sulphate or potassium nitrate in water in a calorimeter and calculate ΔH from temperature change.

Determine ΔH for strong acid–strong base neutralisation in a calorimeter, with emphasis on concordant temperature rises and heat capacity of the calorimeter.

Set up a Daniell-type concentration cell (Zn | Zn²⁺ || Cu²⁺ | Cu) with different ion concentrations and relate emf to the Nernst equation using your readings.

Separate pigments on chromatography paper, mark solvent front, and calculate Rf values from your measured distances.

Systematic tests for unsaturation, alcohol, phenol, aldehyde, ketone, carboxylic acid, and amine/amino groups on assigned organic samples.

Apply Benedict’s, iodine, grease-spot, and biuret (or xanthoproteic) tests to common food samples and record which macronutrients are present.

Practise standardising potassium permanganate against oxalic acid, including the warm-solution technique and spotting the permanent pink end point. Includes viva questions and a place to record your own concordant readings.

Titrate permanganate against ferrous ammonium sulphate in dilute sulphuric acid. Learn why this titration needs no extra indicator and why the acid you choose matters.

Prepare crystals of ferrous ammonium sulphate from ferrous sulphate and ammonium sulphate. Covers dissolving, acidifying, concentrating and crystallising, and what the viva usually asks about double salts.

Make potassium aluminium sulphate crystals and learn how to get well-formed crystals instead of a powder.

Prepare green crystals of potassium trioxalatoferrate(III) from ferric chloride, oxalic acid, and potassium oxalate, then note colour and composition tests.

Acetylate aniline with acetic anhydride to prepare acetanilide crystals — classic Class 12 organic preparation with recrystallisation.

Work through dry and wet tests to identify the anion in an inorganic salt, with a clear record of tests, observations and inferences.

Identify cations by group analysis — NH₄⁺, Pb²⁺, Cu²⁺, As³⁺, Fe³⁺, Al³⁺, Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺, Ba²⁺, Ca²⁺, Sr²⁺, Mg²⁺ — using manual group reagents.