To verify the law of conservation of mass in a chemical reaction. (Experiment – 05)

To verify the law of conservation of mass in a chemical reaction. (Experiment – 05)?

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Experiment-05

AIM:
To verify the law of conservation of mass in a chemical reaction.

MATERIALS REQUIRED

• Barium chloride (BaCl₂.2H₂0)
• sodium sulphate (Na₂SO₄.10H₂O)
• Distilled water.
• two beakers (100 ml), one beaker (150 ml)
• physical balance, spring balance (0-500 g)
• Polythene bag.
• Two watch glasses and a glass rod.

THEORY

1. During a chemical reaction, the mass of the reactants is equal to the mass of the products.
2. Mass can neither be created nor be destroyed.

PROCEDURE

1. Pour 50 ml distilled water in two 100 ml beakers.
2. Weigh 3.6 g of BaCl₂.2H₂0 in a watch glass of known mass and dissolve it in a beaker containing 50 ml distilled water and label it ‘A’.
3. Similarly, weigh 8.05 g of Na₂SO₄.10H₂O in another watch glass of known mass and dissolve it in the other beaker containing 50 mL distilled water. Label it ‘B’.
4. Weigh the 150 ml beaker using spring balance and polythene. Label it ‘C’.
5. Mix solutions of beaker ‘A’ and ‘B’ together in beaker ‘C’. Mix the contents using a glass rod.
6. A white precipitate due to the formation of barium sulphate (BaSO₄) appears in the beaker ‘C’.
7. Weigh the beaker containing the reaction mixture again to find out the mass of products formed.
8. Compare the masses of the contents before and after the reaction.
   

OBSERVATIONS

1. Mass of 50 ml distilled water = 50.0 g
2. Mass of BaCl₂.H₂0 = 3.6 g
3. Mass of BaCl₂ solution = 53.6 g
4. Mass of Na₂SO₄.10H₂O = 8.05 g
5. Mass of Na₂SO₄ solution =58.05 g
6. Total mass of reactants (solutions of BaCl₂ and Na₂SO₄) = 53.6 + 58.05 = 111.65 g
7. Mass of empty 150 ml beaker,m₁ =………………….g
8. Mass of reaction mixture before precipitation, m₂= m₁+ 111.65 g = ……………………g
9. Final mass of reaction mixture after precipitation, m₃ =……………………. g

RESULT

1. On comparing the mass of reactants (m₂) with the mass of products (m₃), we find m₂ equals m₃
2. This proves the law of conservation of mass.

PRECAUTIONS

1. Accurate measurement of masses should be ensured.
2. The spring balance should be held vertical while taking measurements.
3. Before taking reading, ensure the pointer of the spring balance is at zero mark.
4. Use small amount of chemicals.
5. Mix solutions of BaCl₂ and Na₂SO₄ slowly with constant stirring.

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CBSE Class 9 Science Lab Manuals