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State the two important laws of chemical combination. How Dalton’s atomic theory explains the two Laws? |
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Answer» The two important laws of chemical combination are: i) Law of constant proportion: The law states that “in a chemical substance, the elements are always present in definite proportions by mass. For example: In ammonia (NH3), nitrogen and hydrogen are always present in the ratio of 14:3 by mass, whatever the method or source from which it is obtained. In water, hydrogen and oxygen are always present in the ratio of 1:8 by mass, whatever the method or source from which water is obtained. ii) Law of conservation of mass: According to the law of conservation of mass states, atoms are neither created nor destroyed in a chemical reaction. This means that the total mass of the products formed in a chemical reaction must be equal to the mass of reactants consumed. For example: CaCO3 → CaO + CO2 100g 56g 44g Sum of mass of reactants = Sum of masses of prodcuts |
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