CBSE Class 9 Answered
Principle- Law of conservation of mass states that mass can neither created nor destroyed in a chemical reaction.
Total Mass of the Reactant = Total Mass of the Product
Diagram-
Technique- Take a solution of calcium chloride in a flask labeled A, and a solution of sodium sulphate in a test tube labeled B.
Tie a thread to the test tube and carefully lower it in the flask. Cork the flask to make it airtight.
Weigh the flask on a balance. It weighs 300.23 grams.
Tilt and swirl the flask and allow the contents of the test tube to come in contact with the contents of the flask.
Observation- Calcium chloride reacts with sodium sulphate to form a white precipitate of calcium sulphate and a solution of sodium chloride.
Weigh the flask again. There will be no change in the weight of the flask. It again weighs 300.23 grams.
Conclusion- Scientists noticed that if chemical reactions were carried out in a closed container, there is no change in the mass.
The total mass of the reactants is equal to the total mass of the products.