CBSE Practical Exams Preparation 2023: Check Chemistry Class 12th Viva Questions

Surface Chemistry

• Preparation of one lyophilic and one lyophobic sol.
• Lyophilic sol: starch, egg albumin and gum.
• Lyophobic sol: aluminium hydroxide, ferric hydroxide, arsenious sulphide.
• Dialysis of sol prepared in (1) above.
• Study of the role of emulsifying agents in stabilising the emulsions of different oils.

Chemical Kinetics

• Effect of concentration and temperature on the rate of reaction between sodium thiosulphate and hydrochloric acid.

Thermochemistry

• Reaction of iodide ion with hydrogen peroxide at room temperature using different concentrations of iodide ions.
• Reaction between potassium iodate (KIO₃ ) and sodium sulphite (Na₂SO₃) using starch solution as indicator (clock reaction).

Electrochemistry

• Variation of cell potential in Zn|Zn2+||Cu2+|Cu with change in concentration of electrolytes (CuSO4 or ZnSO4) at room temperature.

Chromatography

• Separation of pigments from extracts of leaves and flowers by paper chromatography and determination of Rf values.
• Separation of constituents present in an inorganic mixture containing two cations only (constituents having wide difference in Rf values to be provided).

Preparation of Inorganic Compounds

• Preparation of double salt of ferrous ammonium sulphate or potash alum.
• Preparation of potassium ferric oxalate.

Preparation of Organic Compounds

• Unsaturation, alcoholic, phenolic, aldehydic, ketonic, carboxylic and amino (primary) groups.

Test for the Functional Groups Present in Organic Compounds

Characteristic Tests

• Tests of Carbohydrates Fats and Proteins in Pure Samples and Their Detection in Given Food Stuffs.

Determination of Concentration/Molarity of KMnO4 Solution by Titrating it against a Standard Solution of –

• Oxalic acid
• Ferrous ammonium sulphate

Qualitative Analysis

Determination of one cation and one anion in a given salt.

• Cations:- Pb²⁺, Cu²⁺, As³⁺, Al³⁺, Fe³⁺, Mn²⁺ , Zn²⁺, Cu²⁺, Co²⁺, Ni²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, NH₄⁺
• Anions:- (CO₃)^2‒, S^2‒, (SO₃)^2‒, (SO₄)^2‒, (NO₂)^‒, (SO₄)^2‒, Cl^‒, Br^‒, I^‒, PO₄^3‒, (C₂O₄)^2‒, CH3COO^‒, NO₃^–