Class 12 Chemistry Practical File (NEB)

Volumetric Analysis, Organic Chemistry, Salt Analysis, and Laboratory Preparations

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Introduction

Chemistry is one of the most important branches of science that deals with the composition, structure, properties, and transformations of matter. In the Class 12 curriculum of the National Examination Board (NEB) of Nepal, practical chemistry plays a major role in helping students understand chemical reactions, laboratory techniques, and analytical methods through direct experimentation.

The Class 12 Chemistry Practical File is an essential part of the chemistry course. Students are required to perform different laboratory experiments related to volumetric analysis, organic chemistry, qualitative analysis, and preparation of compounds. These experiments help students connect theoretical concepts with real laboratory observations.

Practical work develops important scientific skills such as:

Careful observation
Accurate measurement
Laboratory handling techniques
Preparation of standard solutions
Detection of functional groups and radicals
Understanding chemical reactions through experiments

Instead of only learning equations and reactions from textbooks, students directly observe color changes, precipitate formation, crystal growth, gas evolution, and oxidation-reduction reactions in the laboratory.

The Class 12 Chemistry practical syllabus includes experiments related to:

Preparation of standard solutions
Acid-base titration
Redox titration
Organic compound analysis
Detection of functional groups
Preparation of inorganic and organic compounds
Salt analysis and identification of radicals

These practical experiments help students improve their understanding of chemistry and prepare them for higher studies and laboratory work.

In this article, we provide a complete overview of the Class 12 Chemistry Practical File according to the NEB syllabus. Students can use this guide to understand experiments and maintain their laboratory notebooks properly.

Index of Class 12 Chemistry Practical Experiments

Preparation of decinormal solution of sodium carbonate
Preparation of decinormal solution of oxalic acid
Determination of strength of HCl solution
Determination of strength of NaOH solution
Determination of strength of KMnO₄ solution
Determination of strength of bench H₂SO₄
Detection of amino functional group
Preparation of potash alum
Preparation of iodoform
Detection of aldehyde functional group
Recovery of blue vitriol crystals
Recovery of calcium carbonate from dolomite
Test for glucose or starch
Test for protein
Test for phenol
Detection of halogen
Detection of nitrogen
Detection of sulfur
Test for unsaturated and saturated fat/oil
Preparation of hydrated calcium sulfate
Identification of acid and basic radicals

1. Preparation of Decinormal Solution of Sodium Carbonate (Na₂CO₃)

In this experiment, students prepare a decinormal (N/10) solution of sodium carbonate using an accurately measured quantity of pure sodium carbonate crystals.

Sodium carbonate is considered a primary standard substance because:

It is highly pure
Stable in air
Easily soluble in water
Does not react quickly with atmosphere

The experiment teaches students how to:

Use analytical balance properly
Transfer chemicals carefully
Use volumetric flask accurately
Prepare standard solutions with exact concentration

The prepared solution is later used in acid-base titration experiments for determining unknown concentrations of acids.

This practical helps students understand the importance of precision and accuracy in quantitative chemistry.

2. Preparation of Decinormal Solution of Oxalic Acid

Oxalic acid is another important primary standard substance used in chemistry laboratories.

In this experiment, students prepare an accurately measured N/10 oxalic acid solution by dissolving a known amount of oxalic acid crystals in distilled water.

This practical develops skills such as:

Correct weighing technique
Safe handling of chemicals
Solution preparation
Proper dilution techniques

The prepared oxalic acid solution is commonly used in:

Redox titration
Standardization of potassium permanganate solution

Students also learn the importance of distilled water and clean apparatus in analytical chemistry.

3. Determination of Strength of Unknown HCl Solution

This experiment involves the determination of concentration or strength of an unknown hydrochloric acid solution using standard sodium carbonate solution.

The reaction between hydrochloric acid and sodium carbonate is a neutralization reaction.

Students perform titration using:

Burette
Pipette
Conical flask
Indicator

Methyl orange indicator changes color at the endpoint, helping students determine the exact amount of acid required for neutralization.

Through this experiment, students learn:

Titration techniques
Reading burette accurately
Calculation of normality and strength
Importance of indicators in chemistry

This experiment is one of the most important practicals in volumetric analysis.

4. Determination of Strength of NaOH Solution

In this practical, sodium hydroxide solution is standardized using hydrochloric acid solution.

NaOH is a strong base and reacts completely with hydrochloric acid.

Phenolphthalein indicator is used because:

It is pink in basic medium
Colorless in acidic medium

During titration, the pink color disappears at the endpoint.

Students gain practical knowledge about:

Acid-base reactions
Use of indicators
Volumetric calculations
Laboratory accuracy and precision

This experiment also improves students’ understanding of neutralization reactions.

5. Determination of Strength of KMnO₄ Solution

Potassium permanganate acts as a powerful oxidizing agent in redox titration.

In this experiment, oxalic acid solution is used to standardize KMnO₄ solution.

The experiment demonstrates:

Oxidation and reduction reactions
Self-indicating property of KMnO₄
Heating during titration
Endpoint detection through permanent light pink color

Students observe how the deep purple color of KMnO₄ disappears until the endpoint is reached.

This experiment helps students understand:

Redox chemistry
Electron transfer reactions
Volumetric analysis techniques

6. Determination of Strength of Bench H₂SO₄

Bench sulfuric acid is a concentrated acid stored in laboratory bottles. Its exact concentration is determined through titration.

Students dilute the acid and standardize it using:

Sodium hydroxide solution
Sodium carbonate solution

This practical teaches:

Safe acid handling
Preparation of dilute solutions
Titration calculations
Chemical stoichiometry

Students also understand why concentrated acids must be diluted carefully.

7. Detection of Amino Functional Group (–NH₂)

Organic compounds containing amino group (–NH₂) are called amines.

The amino group plays an important role in:

Proteins
Amino acids
Pharmaceuticals

Students perform chemical tests that produce characteristic observations such as:

Color changes
Gas evolution
Odor formation

This experiment introduces students to organic functional group analysis and identification techniques.

8. Preparation of Potash Alum (Fitkari)

Potash alum is a double salt commonly known as Fitkari.

Students prepare alum crystals through:

Dissolution
Heating
Filtration
Crystallization

Large transparent crystals are formed when the saturated solution cools slowly.

This experiment helps students understand:

Crystal formation
Solubility
Saturated and supersaturated solutions
Purification techniques

It is one of the most visually attractive chemistry experiments.

9. Preparation of Iodoform

Iodoform is a yellow crystalline compound formed during the iodoform reaction.

The experiment demonstrates:

Organic reaction mechanisms
Formation of precipitates
Characteristic smell of iodoform

The appearance of yellow crystals confirms the reaction.

This experiment is important in identifying certain alcohols and carbonyl compounds.

10. Detection of Aldehyde Functional Group

Aldehydes are organic compounds containing the –CHO group.

Students use tests such as:

Tollens’ test
Fehling’s test

Characteristic observations include:

Silver mirror formation
Brick-red precipitate

These reactions help students identify aldehydes and distinguish them from ketones.

11. Recovery of Blue Vitriol Crystals

Blue vitriol is hydrated copper sulfate crystal.

Students recover crystals from a mixture through:

Dissolution
Filtration
Evaporation
Crystallization

This practical demonstrates purification techniques used in chemistry laboratories.

12. Recovery of Calcium Carbonate from Dolomite

Dolomite contains calcium carbonate and magnesium carbonate.

Students chemically separate calcium carbonate from the mixture.

The experiment helps students understand:

Double decomposition reactions
Filtration methods
Precipitation reactions

13. Test for Glucose or Starch

Students test food samples for carbohydrates.

Tests Used

Iodine test for starch
Benedict’s test for glucose

Color changes indicate the presence of carbohydrates.

This experiment helps students understand biochemical testing methods.

14. Test for Protein

Proteins are tested using the Biuret test.

A violet or purple coloration confirms protein presence.

Students learn about:

Protein chemistry
Biochemical reactions
Role of copper ions in testing proteins

15. Test for Phenol

Phenol reacts with ferric chloride to produce violet coloration.

This experiment demonstrates:

Organic compound testing
Aromatic chemistry
Functional group analysis

Phenols are important industrial and medicinal compounds.

16. Detection of Halogen

Halogens are detected using sodium fusion extract and silver nitrate test.

17. Detection of Nitrogen

Nitrogen is detected using Lassaigne’s test producing Prussian blue coloration.

18. Detection of Sulfur

Sulfur is identified through black precipitate formation or violet coloration.

19. Test for Unsaturated and Saturated Fat/Oil

Unsaturated fats decolorize bromine water due to double bonds.

20. Preparation of Hydrated Calcium Sulfate from Marble Chips

Hydrated calcium sulfate (gypsum) is prepared chemically from marble chips.

21. Identification of Acid and Basic Radicals

Salt analysis involves identification of:

Acid radicals (anions)
Basic radicals (cations)

Students observe:

Color changes
Gas evolution
Precipitate formation

Conclusion

Chemistry practical experiments help students understand chemical reactions and laboratory techniques through direct experimentation. The Class 12 NEB Chemistry practical syllabus includes important activities related to volumetric analysis, organic chemistry, qualitative analysis, and preparation of compounds.

Maintaining a proper practical file helps students organize observations, calculations, and experimental results effectively.

Thank You

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