Question

To verify the law of conservation of mass in a chemical reaction class 9

Answer 1

Step 1: 100 mL distilled water is poured in two beakers (150 mL).

Step 2: The physical balance and a watch glass of known mass are used, weigh 7.2 g of BaCl2 .2H2O and dissolved in a beaker (150 mL) containing 100 mL distilled water.

Step 3: Similarly, 16.1 g of Na2SO4.10H2O is weighed in another watch glass of known mass and dissolved in another beaker (150 mL) containing 100 mL distilled water.

Step 4: The third beaker (250 mL) is taken and weighed using a spring balance and polythene bag.

Step 5: Both solutions of 150 mL beakers is mixed in the third beaker (250 mL). The contents are mixed using a glass stirrer.

Step 6: White precipitate of BaSO4 appears on mixing due to precipitation reaction.

Step 7: The beaker containing the reaction mixture is weighed again to determine the mass of the precipitation reaction products.

Step 8: The masses of before and after the chemical reaction are compared.

Answer 2

Answer:

Compare the initial mass (m2) of the reaction mixture (before the precipitation) with the final mass (m3) of the reaction mixture (after the precipitation). If the two masses are same within the reasonable limits, then the law of conservation of mass stands verified.