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.
- 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.
- During a chemical reaction, the mass of the reactants is equal to the mass of the products.
- Mass can neither be created nor be destroyed.
- Pour 50 ml distilled water in two 100 ml beakers.
- 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’.
- 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’.
- Weigh the 150 ml beaker using spring balance and polythene. Label it ‘C’.
- Mix solutions of beaker ‘A’ and ‘B’ together in beaker ‘C’. Mix the contents using a glass rod.
- A white precipitate due to the formation of barium sulphate (BaSO4) appears in the beaker ‘C’.
- Weigh the beaker containing the reaction mixture again to find out the mass of products formed.
- Compare the masses of the contents before and after the reaction.
- Mass of 50 ml distilled water = 50.0 g
- Mass of BaCl2.H20 = 3.6 g
- Mass of BaCl2 solution = 53.6 g
- Mass of Na2SO4.10H2O = 8.05 g
- Mass of Na2SO4 solution =58.05 g
- Total mass of reactants (solutions of BaCl2 and Na2SO4) = 53.6 + 58.05 = 111.65 g
- Mass of empty 150 ml beaker,m1 =………………….g
- Mass of reaction mixture before precipitation, m2= m1+ 111.65 g = ……………………g
- Final mass of reaction mixture after precipitation, m3 =……………………. g
- On comparing the mass of reactants (m2) with the mass of products (m3), we find m2 equals m3
- This proves the law of conservation of mass.
- Accurate measurement of masses should be ensured.
- The spring balance should be held vertical while taking measurements.
- Before taking reading, ensure the pointer of the spring balance is at zero mark.
- Use small amount of chemicals.
- Mix solutions of BaCl2 and Na2SO4 slowly with constant stirring.