Q.1 In what respect does Dalton’s Atomic theory hold good even today? However, he assumed that the simplest compound of two elements Using his theory, Dalton rationalized the various laws of chemical combination which were in existence at that time. Mass can neither be created nor destroyed in a chemical reaction.įor any chemical process in a closed system, the mass of the reactants must be equal the mass of the products.Ĭ + O 2 = CO 212g +32g = 44g 2. Proposed by the French chemist Antoine Lavoisier (1774) Q.2 Calculate the ratio of atoms present in 5 g of magnesium and 5 g of iron. Q.1 Why chemical reactions are in accordance with the Law of conservation of mass? This law does not hold good when the compound is obtained by using different Limitation of “Law of definite proportion” Weight before the reaction = Weight after the reaction When the tube is weighed again it is observed that: The whole tube is kept undisturbed for sometime so that the reaction is complete. The two reactants are made to react by inverting the tube. The tube is sealed and weighed precisely. Verification of “Law of Conservation of mass”Ī solution of sodium chloride and silver nitrate are taken separately in the two limbs of an ’H’ shaped tube. Notes of Chemistry for Class 9 CHAPTER 3 ATOMS AND MOLECULES
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