CLASS 10 CBSE CHEMISTRY PRACTICAL

EXPERIMENT: Performing and Observing Chemical Reactions and Classifying them as Combination, Decomposition, Displacement, and Double Displacement Reactions

AIM:

To perform and observe the following reactions and classify them into:

  • Combination reaction
  • Decomposition reaction
  • Displacement reaction
  • Double displacement reaction

Reactions to be studied:

  1. Action of water on quicklime
  2. Action of heat on ferrous sulphate crystals
  3. Iron nails kept in copper sulphate solution
  4. Reaction between sodium sulphate and barium chloride solutions

MATERIALS REQUIRED:

  1. Test tubes (4)
  2. Test tube stand
  3. Test tube holder
  4. Beaker (250 mL)
  5. Boiling tube
  6. Burner
  7. Quicklime (CaO)
  8. Ferrous sulphate crystals (FeSO₄.7H₂O)
  9. Iron nails (clean and rust-free)
  10. Copper sulphate solution (CuSO₄)
  11. Sodium sulphate solution (Na₂SO₄)
  12. Barium chloride solution (BaCl₂)
  13. Dropper
  14. Distilled water

THEORY:

Types of Chemical Reactions:

1. Combination Reaction:
A reaction in which two or more reactants combine to form a single product.

  • General form: A + B → AB
  • Example: CaO + H₂O → Ca(OH)₂

2. Decomposition Reaction:
A reaction in which a single reactant breaks down into two or more products, usually by heating, light, or electricity.

  • General form: AB → A + B
  • Example: 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃

3. Displacement Reaction:
A reaction in which a more reactive element displaces a less reactive element from its compound.

  • General form: A + BC → AC + B
  • Example: Fe + CuSO₄ → FeSO₄ + Cu

4. Double Displacement Reaction:
A reaction in which two compounds exchange their ions to form two new compounds.

  • General form: AB + CD → AD + CB
  • Example: Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl

PROCEDURE:

Experiment 1: Action of Water on Quicklime (Combination Reaction)

  1. Take a beaker and add a small piece of quicklime (CaO) to it.
  2. Carefully add about 50 mL of water to the beaker.
  3. Touch the outer surface of the beaker and observe.
  4. Note any change in temperature and appearance.
  5. Record your observations.

Experiment 2: Action of Heat on Ferrous Sulphate Crystals (Decomposition Reaction)

  1. Take a clean, dry boiling tube.
  2. Add about 2 g of ferrous sulphate crystals (green color) to it.
  3. Hold the boiling tube with a test tube holder.
  4. Heat the boiling tube over a burner flame gently at first, then strongly.
  5. Observe the color change of the crystals and smell carefully (from a distance).
  6. Note the formation of any gases and residue.
  7. Record your observations.

Experiment 3: Iron Nails in Copper Sulphate Solution (Displacement Reaction)

  1. Take a clean test tube.
  2. Pour about 10 mL of copper sulphate solution (blue color) into it.
  3. Take 2-3 clean iron nails and immerse them in the copper sulphate solution.
  4. Keep the test tube undisturbed for about 15-20 minutes.
  5. Observe the color change of the solution and the coating on iron nails.
  6. Record your observations.

Experiment 4: Reaction between Sodium Sulphate and Barium Chloride (Double Displacement Reaction)

  1. Take a clean test tube.
  2. Pour about 5 mL of sodium sulphate solution into it.
  3. Add about 5 mL of barium chloride solution to the same test tube using a dropper.
  4. Observe the formation of any precipitate.
  5. Note the color and nature of the precipitate.
  6. Record your observations.

OBSERVATION:

Table: Observations and Classification of Reactions

S. No.ExperimentReactantsObservationProductsType of Reaction
1Action of water on quicklimeCaO + H₂O• Vigorous reaction
• Hissing sound
• Beaker becomes hot (exothermic)
• White slaked lime formed		Ca(OH)₂ (Calcium hydroxide)Combination Reaction
2Action of heat on ferrous sulphateFeSO₄.7H₂O• Green crystals turn brown/reddish
• Smell of burning sulphur (SO₂)
• Water droplets appear on the tube
• Residue is Fe₂O₃ (ferric oxide)		Fe₂O₃ + SO₂ + SO₃ + H₂ODecomposition Reaction
3Iron nails in copper sulphateFe + CuSO₄• Blue color of solution fades
• Solution becomes light green
• Reddish-brown coating on iron nails
• Copper deposited on nails		FeSO₄ + CuDisplacement Reaction
4Sodium sulphate + Barium chlorideNa₂SO₄ + BaCl₂• White precipitate formed immediately
• Precipitate settles at bottom
• Solution remains clear		BaSO₄↓ (white ppt) + 2NaClDouble Displacement Reaction

CHEMICAL EQUATIONS:

1. Combination Reaction:

CaO + H₂O → Ca(OH)₂ + Heat
(Quicklime) (Water) (Slaked lime)

2. Decomposition Reaction:

2FeSO₄.7H₂O --Heat--> Fe₂O₃ + SO₂ + SO₃ + 14H₂O
(Ferrous sulphate) (Ferric oxide) (Sulphur dioxide) (Sulphur trioxide) (Water)
(Green crystals) (Brown residue)

3. Displacement Reaction:

Fe + CuSO₄ → FeSO₄ + Cu
(Iron) (Copper sulphate) (Ferrous sulphate) (Copper)
(Blue solution) (Light green solution) (Reddish-brown coating)

4. Double Displacement Reaction:

Na₂SO₄ + BaCl₂ → BaSO₄↓ + 2NaCl
(Sodium sulphate) (Barium chloride) (Barium sulphate) (Sodium chloride)
(White precipitate)

RESULT:

The following reactions were performed and classified as:

  1. Action of water on quicklime – Combination Reaction
  2. Action of heat on ferrous sulphate crystals – Decomposition Reaction
  3. Iron nails in copper sulphate solution – Displacement Reaction
  4. Sodium sulphate + Barium chloride – Double Displacement Reaction

PRECAUTIONS:

  1. Handle quicklime carefully as it is corrosive and the reaction is highly exothermic.
  2. Do not touch the beaker immediately after adding water to quicklime.
  3. While heating ferrous sulphate crystals, hold the test tube with a holder and point it away from yourself and others.
  4. Do not smell the gases directly; waft them gently toward your nose from a distance.
  5. Use clean and rust-free iron nails for accurate results in the displacement reaction.
  6. Wear safety goggles while performing the experiments.
  7. Handle chemicals carefully and avoid direct contact with skin.
  8. Perform experiments in a well-ventilated area.
  9. Heat the test tube gently at first to avoid cracking.
  10. Dispose of chemicals as per laboratory guidelines.
  11. Clean all apparatus after use.
  12. Wash hands thoroughly after completing the experiment.

Signature of Teacher: ___

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