Advanced Study Material for Class 12 Chemistry: Preparation Of Reagents
Review targeted academic resources with the Class 12 Chemistry Practicals Preparation Of Reagents. Built according to official CBSE standards for the 2026-27 term, these downloadable Class 12 Chemistry study materials support effective daily practice and deeper conceptual understanding for Preparation Of Reagents.
Practice Class 12 Chemistry Resources: Preparation Of Reagents
Navigate directly to the advanced Chemistry study materials using the digital viewer below. Each resource pack includes detailed conceptual summaries and solved practice questions, allowing students to instantly reinforce their learning.
PREPARATION OF REAGENTS
Salt Analysis
1. Ammonium acetate : 230 g / Litre [1 Mark]
Answer:
1. Weigh 230 g of ammonium acetate.
2. Dissolve it in a small amount of distilled water and make up the total volume to 1 Litre.
Teacher's Note:
a) Ammonium acetate is commonly used as a buffer solution in salt analysis.
b) Always use clean glassware and distilled water for preparing standard reagent solutions.
2. Ammonium carbonate : 160 gm / Litre + 140 ml liquor ammonia [1 Mark]
Answer:
1. Dissolve 160 gm of ammonium carbonate in distilled water.
2. Add 140 ml of liquor ammonia and dilute the mixture to 1 Litre.
Teacher's Note:
a) Liquor ammonia prevents the premature precipitation of group V carbonates.
b) Store the solution in a tightly stoppered bottle to prevent loss of ammonia gas.
3. Ammonium chloride : 270 gm / Litre [1 Mark]
Answer:
1. Weigh 270 gm of ammonium chloride.
2. Dissolve in distilled water and make up the volume to 1 Litre.
Teacher's Note:
a) Used in group III precipitation to suppress the concentration of hydroxide ions.
b) Ensure complete dissolution by stirring thoroughly.
4. Ammonium hydroxide : 270 ml Liquor Ammonia / Litre [1 Mark]
Answer:
1. Measure 270 ml of concentrated liquor ammonia.
2. Dilute with distilled water to a final volume of 1 Litre.
Teacher's Note:
a) Prepared in a fume cupboard due to the pungent smell of ammonia.
b) Used as a basic reagent for group III and group IV analysis.
5. Ammonium oxalate : 35 gm / Litre [1 Mark]
Answer:
1. Weigh 35 gm of ammonium oxalate monohydrate.
2. Dissolve in distilled water and make up the volume to 1 Litre.
Teacher's Note:
a) Specific reagent for the detection and precipitation of calcium ions as calcium oxalate.
b) Gentle warming may be required to dissolve the salt completely.
6. Ammonium thiocyanate : 38 gm / Litre [1 Mark]
Answer:
1. Weigh 38 gm of ammonium thiocyanate.
2. Dissolve in distilled water and make up to 1 Litre.
Teacher's Note:
a) Used as a confirmatory test reagent for ferric (Fe3+) ions, producing a blood-red complex.
b) Handle with care as thiocyanates are toxic upon ingestion.
7. Barium chloride : 61 gm / Litre [1 Mark]
Answer:
1. Weigh 61 gm of barium chloride dihydrate.
2. Dissolve in distilled water and dilute to 1 Litre.
Teacher's Note:
a) Standard group reagent for detecting sulfate and sulfite radicals.
b) Barium salts are highly toxic; avoid skin contact and ingestion.
8. Cobalt nitrate : 44 gm / Litre [1 Mark]
Answer:
1. Weigh 44 gm of cobalt nitrate.
2. Dissolve in distilled water and make up the volume to 1 Litre.
Teacher's Note:
a) Used in cobalt nitrate charcoal test for identifying aluminum, zinc, and magnesium oxides.
b) Produces characteristic colored residues on heating.
9. Dil. Acetic acid : 300 ml / Litre [1 Mark]
Answer:
1. Measure 300 ml of glacial acetic acid.
2. Add to distilled water and make up the total volume to 1 Litre.
Teacher's Note:
a) Used as a weak acid medium in various confirmatory tests.
b) Always add acid to water slowly with stirring.
10. Dil. Hydrochloric acid : 400 ml / Litre [1 Mark]
Answer:
1. Measure 400 ml of concentrated hydrochloric acid.
2. Pour slowly into distilled water and dilute to 1 Litre.
Teacher's Note:
a) Essential for dissolving original salt samples and group separation.
b) Exothermic dilution requires constant stirring and cooling.
11. Dil. Nitric acid : 300 ml / Litre [1 Mark]
Answer:
1. Measure 300 ml of concentrated nitric acid.
2. Add carefully to distilled water to make 1 Litre of solution.
Teacher's Note:
a) Used for preparing solutions for group II separation and oxidizing interfering radicals.
b) Nitric acid is a strong oxidizing agent; handle with extreme caution.
12. Dil. Sulphuric acid : 150 ml / Litre [1 Mark]
Answer:
1. Measure 150 ml of concentrated sulfuric acid.
2. Slowly pour into distilled water with constant stirring and make up to 1 Litre.
Teacher's Note:
a) Used in permanganate titrations and preliminary acid radical tests.
b) Never add water to concentrated sulfuric acid due to extreme heat release.
13. Di-sodium hydrogen phosphate : 120 ml / Litre [1 Mark]
Answer:
1. Weigh 120 gm of di-sodium hydrogen phosphate.
2. Dissolve in distilled water and dilute to 1 Litre.
Teacher's Note:
a) Used as a precipitating reagent for magnesium ions.
b) Ensure complete dissolution before storing.
14. Lead acetate : 95 gm / Litre + 15 ml acetic acid [1 Mark]
Answer:
1. Weigh 95 gm of lead acetate and dissolve in distilled water.
2. Add 15 ml of acetic acid to prevent hydrolysis and make up the total volume to 1 Litre.
Teacher's Note:
a) Acetic acid suppresses the formation of basic lead carbonate precipitate.
b) Lead compounds are poisonous; wash hands thoroughly after use.
15. Potassium chromate : 20 gm / Litre + 15 ml acetic acid [1 Mark]
Answer:
1. Dissolve 20 gm of potassium chromate in distilled water.
2. Add 15 ml of acetic acid and dilute to 1 Litre.
Teacher's Note:
a) Used for precipitating lead and barium chromates.
b) Chromates are toxic and suspected carcinogens.
16. Potassium ferrocyanide : 55 gm / Litre [1 Mark]
Answer:
1. Weigh 55 gm of potassium ferrocyanide.
2. Dissolve in distilled water and make up the volume to 1 Litre.
Teacher's Note:
a) Serves as a specific reagent for detecting ferric and cupric ions.
b) Store in an amber-colored bottle away from direct sunlight.
17. Potassium iodide : 33 gm / Litre [1 Mark]
Answer:
1. Weigh 33 gm of potassium iodide.
2. Dissolve in distilled water and dilute to 1 Litre.
Teacher's Note:
a) Used in testing for lead, mercury, and oxidizing agents.
b) Protect solution from light to prevent oxidation to iodine.
18. Silver nitrate : 17 gm / Litre of distilled water [1 Mark]
Answer:
1. Weigh 17 gm of silver nitrate crystals.
2. Dissolve strictly in distilled water and make up to 1 Litre.
Teacher's Note:
a) Distilled water is mandatory to prevent premature precipitation of silver chloride by tap water chlorides.
b) Store in dark brown bottles because silver nitrate is photosensitive.
19. Sodium hydroxide : 200 gm / Litre of distilled water [1 Mark]
Answer:
1. Weigh 200 gm of sodium hydroxide pellets.
2. Dissolve cautiously in distilled water and dilute to 1 Litre.
Teacher's Note:
Dissolution is highly exothermic; handle with rubber gloves and safety goggles.
Teacher's Note:
a) Used for group analysis and identifying various cations.
b) Store in plastic bottles with tight caps as glass stoppers can jam.
20. Starch solution : Add 1 gm / 10 ml of water starch paste into 90 ml of boiling water. [1 Mark]
Answer:
1. Mix 1 gm of starch with 10 ml of cold water to form a smooth paste.
2. Pour this paste slowly into 90 ml of boiling water with constant stirring and boil for a minute.
Teacher's Note:
a) Used as an indicator in iodometric and iodimetric titrations.
b) Freshly prepared starch solution should be used for accurate endpoint detection.
21. Lime water : Dissolve 1.7 gm of lime or 2.5 gm of Calcium hydroxide in one litre of water. Decant the solution after long standing. [1 Mark]
Answer:
1. Dissolve 1.7 gm of quicklime or 2.5 gm of calcium hydroxide in 1 Litre of water.
2. Allow the mixture to stand for a long time and decant the clear supernatant liquid.
Teacher's Note:
a) Used for detecting carbon dioxide gas, turning it milky.
b) Decantation ensures only clear saturated solution is used.
22. Nessler’s Reagent : Dissolve 10 gm of potassium iodide in 10 ml of water. To this add saturated solution of mercuric chloride (60 gm/litre) in small quantities at a time with shaking, until a slight permanent reddish precipitate forms. With this add 80 ml of 9N Sodium hydroxide solution and diluted to 200 ml. Allow it to stand overnight. Decant the solution next day and store in a dark place. [1 Mark]
Answer:
1. Dissolve 10 gm of potassium iodide in 10 ml of water and add saturated mercuric chloride until a permanent precipitate forms.
2. Add 80 ml of 9N sodium hydroxide, dilute to 200 ml, stand overnight, decant, and store in the dark.
Teacher's Note:
a) Highly sensitive reagent used for detecting ammonium ions, giving a brown coloration.
b) Mercuric compounds are extremely toxic and require careful disposal.
23. Aluminium Reagent : Dissolve 0.25 gm of aluminon (Ammonium salt of aurine tricarboxylic acid) in 250 ml of distilled water. [1 Mark]
Answer:
1. Weigh 0.25 gm of aluminon.
2. Dissolve in distilled water and make up the total volume to 250 ml.
Teacher's Note:
a) Used for the lake test to confirm the presence of aluminum ions.
b) Produces a bright red lake precipitate in the presence of an alkaline medium.
24. Magneson Reagent : Dissolve 0.001 gm of magneson (p-nitro benezene azo resorcinol) in 100 ml of 1 N sodium hydroxide. [1 Mark]
Answer:
1. Weigh 0.001 gm of magneson.
2. Dissolve in 100 ml of 1 N sodium hydroxide solution.
Teacher's Note:
a) Used for identifying magnesium ions through a characteristic blue lake test.
b) Requires precise weighing due to the very small quantity needed.
25. Hydrogen Sulphide gas : Allow ferrous sulphide to react with dilute sulphuric acid in Kipp’s apparatus. Instead Yellow Ammonium suplhide solution can be used. [1 Mark]
Answer:
1. Set up Kipp's apparatus containing ferrous sulphide pieces.
2. Add dilute sulfuric acid to generate hydrogen sulphide gas on demand.
Teacher's Note:
a) Essential reducing agent and group precipitating gas for group II and IV basic radicals.
b) Hydrogen sulphide has a foul rotten-egg smell and is toxic; generation must be done in a fume hood.
Volumetric Analysis:
1. Ferrous ammonium sulphate (1N) : 392 gm FAS paste in 100 ml conc. H2SO4 / litre water. [1 Mark]
Answer:
1. Weigh 392 gm of ferrous ammonium sulphate (Mohr's salt).
2. Dissolve with 100 ml of concentrated sulfuric acid and dilute to 1 Litre with water.
Teacher's Note:
a) Acid is added to prevent the hydrolysis and oxidation of ferrous ions to ferric ions.
b) FAS is a primary standard salt used in redox titrations.
2. Oxalic acid (1 N) : 63g / litre [1 Mark]
Answer:
1. Weigh 63 g of oxalic acid dihydrate.
2. Dissolve in distilled water and make up the volume to 1 Litre.
Teacher's Note:
a) Equivalent weight of oxalic acid dihydrate is 63 g/eq.
b) Acts as a primary standard in titrations against potassium permanganate.
3. Pottassium permanganate (1 N) : 31.6 g / litre. [1 Mark]
Answer:
1. Weigh 31.6 g of potassium permanganate.
2. Dissolve in distilled water and dilute to 1 Litre.
Teacher's Note:
a) Equivalent weight in acid medium is 158 / 5 = 31.6 g/eq.
b) Solution is usually standardized before use as it is not a primary standard.
4. Ferrous sulphate (1 N) : 278 g / litre + little con. H2SO4. [1 Mark]
Answer:
1. Weigh 278 g of ferrous sulphate heptahydrate.
2. Dissolve in water, add a small amount of concentrated sulfuric acid, and make up to 1 Litre.
Teacher's Note:
a) Sulfuric acid prevents atmospheric oxidation of ferrous ions.
b) Must be freshly prepared for accurate volumetric results.
5. Sulphuric acid (2 N) : 55 ml / litre [1 Mark]
Answer:
1. Measure 55 ml of concentrated sulfuric acid.
2. Pour slowly into distilled water and dilute to 1 Litre.
Teacher's Note:
a) Used to provide an acidic medium for redox titrations.
b) Always exercise caution when diluting concentrated acids.
6. 0.1 N solutions : 100 ml of 1 N solution/litre [1 Mark]
Answer:
1. Measure 100 ml of the 1 N stock solution.
2. Dilute with distilled water to a total volume of 1 Litre.
Teacher's Note:
a) Based on the dilution formula \(N_1V_1 = N_2V_2\).
b) Convenient method for preparing lower normality solutions from standard stocks.
7. 0.05 N solutions : 50 ml of 1 N solution per litre. (For economical use and accuracy of results.) [1 Mark]
Answer:
1. Measure 50 ml of the 1 N stock solution.
2. Dilute with distilled water to a final volume of 1 Litre.
Teacher's Note:
a) Dilute solutions reduce reagent consumption and chemical waste.
b) Ensure thorough mixing after dilution to maintain homogeneity.
Note : Never add water to a concentrated acid. Instead concentrated acid is added to water with constant stirring. [1 Mark]
Answer:
1. Always pour the denser, concentrated acid slowly into water while stirring continuously.
2. This dissipates the heat generated safely and prevents dangerous acid splattering.
Teacher's Note:
a) Mixing water into acid causes localized boiling and violent splashing due to high exothermicity.
b) Fundamental safety rule in all chemical laboratories.
Free study material for Chemistry
Chemistry Class 12 Exam Resources: Preparation Of Reagents
Essential Notes for Class 12 Chemistry
Access comprehensive study material for Preparation Of Reagents, including revision notes, concept maps, and high-probability questions. These resources are designed in alignment with the latest 2026 CBSE syllabus for Class 12 Chemistry to support effective exam preparation.
Verified Solutions for Class 12 Chemistry
Designed around the official curriculum, these study guides guarantee standard compliance. Reviewing step-by-step solutions clarifies complex sub-topics within Preparation Of Reagents and demystifies standard marking schemes for Chemistry evaluations.
Enhance Accuracy with Online Tests
Wrap up your chapter revision by testing your knowledge against standard objective question formats. Explore our full library of free, up-to-date sample papers and online assessments to secure top grades in your CBSE examinations.
FAQs
Our advanced study package for Preparation Of Reagents includes detailed concepts, diagrams, Mind Maps, and explanation of complex topics to ensure Class 12 students learn as per syllabus for 2026 exams.
The Mind Maps provided for Preparation Of Reagents act as visual anchors which will help faster recall during high-pressure exams.
Yes, teachers use our Class 12 Chemistry resources for lesson planning as they are in simple language and have lot of solved examples.
Yes, You can download the complete, mobile-friendly PDF of the Chemistry Preparation Of Reagents advanced resources for free.
Yes, our subject matter experts have updated the Preparation Of Reagents material to align with the rationalized NCERT textbooks and have removed deleted topics and added new competency-based questions.