Class 12 Chemistry Lab Manual – Preparation of Inorganic Compounds

The preparation of inorganic compounds is an important part of Class 12 Chemistry practicals. It involves the synthesis of pure crystalline salts and other inorganic substances through chemical reactions such as double displacement, precipitation, or neutralization. These experiments help students understand chemical reactions, crystallization techniques, and the concept of purity in compounds. Practical examinations, conducted under the supervision of the Central Board of Secondary Education, assess students on their ability to carry out experiments accurately, record observations, and answer viva questions effectively.

Practical knowledge in the preparation of inorganic compounds builds laboratory skills, observation precision, and understanding of chemical reactions. Studentbro.in provides a step-by-step, structured guide to help Class 12 students master these experiments.

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Importance of Preparing Inorganic Compounds in Practical Experiments

Studying the preparation of inorganic compounds in the laboratory allows students to:

• Learn crystallization and precipitation techniques

• Understand chemical reactions and stoichiometry

• Develop accuracy in handling chemicals and apparatus

• Improve analytical and observation skills

• Connect theoretical chemical equations with practical outcomes

Hands-on experience ensures better understanding of chemistry concepts and prepares students for practical exams.

Objectives of Preparation of Inorganic Compounds Experiments

The main objectives include:

• To synthesize pure inorganic compounds from given reactants

• To learn and apply crystallization and precipitation techniques

• To study factors affecting crystal formation

• To improve accuracy in measuring and handling reagents

• To develop skills in recording observations and analyzing results

Achieving these objectives helps students understand the practical aspects of inorganic chemistry.

Principles of Preparation of Inorganic Compounds Experiments

These experiments are based on the following principles:

• Double Displacement Reactions – Formation of insoluble salts by exchanging ions

• Precipitation – Separation of solid products from solution

• Crystallization – Formation of pure crystals by controlled evaporation or cooling

• Stoichiometry – Accurate measurement of reactants for complete reaction

• Purity and Filtration – Techniques to obtain pure products by removing impurities

Understanding these principles ensures proper execution and reliable results.

Common Experiments in Preparation of Inorganic Compounds

1. Preparation of Copper Sulphate Crystals

   • Principle: Copper reacts with dilute sulfuric acid to form blue copper sulfate crystals.

   • Apparatus: Beakers, glass rod, watch glass, funnel, filter paper, copper metal, dilute H₂SO₄.

   • Procedure: React copper with acid, filter the solution, evaporate slowly to obtain crystals.

   • Observation: Formation of blue crystals; measure size and yield.

2. Preparation of Ferrous Ammonium Sulfate (Mohr’s Salt)

   • Principle: Double salt formation via reaction of FeSO₄ and (NH₄)₂SO₄.

   • Apparatus: Beakers, stirring rod, funnel, filter paper, watch glass, FeSO₄·7H₂O, (NH₄)₂SO₄.

   • Procedure: Dissolve reagents, mix under controlled temperature, crystallize by slow cooling.

   • Observation: Formation of pale green crystals; record yield.

3. Preparation of Potash Alum

   • Principle: Crystallization of K₂SO₄·Al₂(SO₄)₃·24H₂O by mixing aluminum sulfate and potassium sulfate.

   • Apparatus: Beakers, stirrer, filter paper, funnel, watch glass.

   • Procedure: Mix solutions, filter impurities, allow slow evaporation for crystal formation.

   • Observation: Formation of octahedral crystals; note size and purity.

4. Preparation of Sodium Potassium Tartrate Crystals

   • Principle: Double salt formation by mixing tartaric acid and alkaline hydroxides.

   • Apparatus: Beakers, stirring rod, filter paper, funnel, watch glass, NaOH, KOH, tartaric acid.

   • Procedure: Dissolve acid in alkaline solution, filter, crystallize by slow evaporation.

   • Observation: Needle-shaped or prism-shaped crystals; measure yield.

These experiments help students develop understanding of reaction types, purification methods, and crystallization techniques.

Apparatus Required for Preparation of Inorganic Compounds

• Beakers, measuring cylinders, and glass rods

• Funnels and filter paper

• Watch glass and evaporating dishes

• Stirring rods and spatulas

• Chemicals: copper metal, FeSO₄·7H₂O, (NH₄)₂SO₄, K₂SO₄, Al₂(SO₄)₃, tartaric acid, NaOH, KOH, dilute acids

• Safety equipment: gloves, goggles, lab coat

Familiarity with apparatus ensures safe handling and accurate results.

Experimental Setup

• Place beakers and evaporating dishes on a stable, clean surface

• Measure chemicals accurately using weighing balance or graduated cylinders

• Stir solutions gently to avoid spillage

• Allow crystals to form slowly for purity

• Filter solutions carefully to remove insoluble impurities

• Use proper labeling of solutions and samples

A systematic setup ensures reliable and reproducible results.

Observation Tables and Recording Results

Observation tables include:

• Name of compound prepared

• Physical appearance of crystals (color, shape)

• Mass of product obtained

• Reaction conditions (temperature, duration)

• Yield calculation

• Notes on purity or contamination

Systematic recording is essential for proper analysis and viva preparation.

Calculations and Results

Students should:

• Calculate percentage yield using formula:

Percentage Yield=Actual YieldTheoretical Yield×100\text{Percentage Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100Percentage Yield=Theoretical YieldActual Yield​×100

• Record crystal size and quality

• Compare experimental yield with theoretical expectations

• Present step-by-step calculations for clarity

Accurate calculations reinforce understanding of stoichiometry and chemical reactions.

Precautions for Preparation of Inorganic Compounds Experiments

• Use clean and dry apparatus to avoid contamination

• Measure chemicals accurately

• Maintain controlled temperature for crystallization

• Avoid rapid evaporation to ensure pure crystals

• Wear gloves, goggles, and lab coat

• Handle acids and bases carefully

Precautions ensure safety, accuracy, and reproducibility of results.

Common Mistakes to Avoid

• Using impure reagents

• Overheating solutions during crystallization

• Disturbing crystals while forming

• Improper filtration leading to impurities

• Neglecting safety precautions

Avoiding mistakes ensures reliable results and high marks.

Viva Questions on Preparation of Inorganic Compounds

• Explain the principle of crystallization

• How do you ensure purity of crystals?

• What are double salts, and give examples

• How is percentage yield calculated?

• What precautions are necessary during crystallization?

• Explain the reaction involved in the preparation of copper sulfate crystals

Viva preparation ensures confident responses during practical exams.

Marking Scheme for Inorganic Compounds Practical

Marks are awarded based on:

• Correct experimental setup and procedure

• Accuracy in measurement and reaction execution

• Purity, appearance, and yield of crystals

• Neat diagrams and recorded tables

• Completion of practical record

• Viva answers

A complete and well-documented report ensures maximum marks.

Applications of Preparation of Inorganic Compounds

Practical knowledge in preparing inorganic compounds is useful in:

• Industrial production of salts and chemicals

• Laboratory preparation and quality testing of materials

• Education and research experiments

• Pharmaceutical and chemical manufacturing

• Understanding chemical reaction principles and crystallization techniques

Hands-on preparation of compounds connects theoretical knowledge with practical chemical applications.

How Studentbro.in Supports Class 12 Chemistry Students

Studentbro.in provides:

• Step-by-step guidance for preparation of inorganic compounds

• Apparatus handling and setup instructions

• Observation table templates and calculation examples

• Viva question bank and preparation strategies

• Safety and precaution tips aligned with CBSE syllabus

Our resources equip students with structured, reliable, and exam-focused preparation.

Conclusion

Preparation of inorganic compounds experiments is crucial for understanding chemical reactions, crystallization, and purity of substances. Accurate measurement, systematic observation, careful handling, and proper calculation are key to performing well in practical examinations.

By following CBSE guidelines and regular practice, students can confidently perform inorganic compound preparation experiments and achieve excellent results.

Studentbro.in provides comprehensive, easy-to-understand, and exam-oriented resources to support Class 12 students in mastering Chemistry practicals.