UNIT I: Some Basic Concepts of Chemistry
Unit II: Structure of Atom
Unit III: Classification of Elements and Periodicity in Properties
Unit IV: Chemical Bonding and Molecular Structure
Unit V: States of Matter: Gases and Liquids
Unit VI: Chemical Thermodynamics
Unit VII: Equilibrium
Unit VIII: Redox Reaction
Unit IX: Hydrogen
Unit X: s -Block Elements (Alkali and Alkaline Earth Metals)
UNIT XI: P -BLOCK ELEMENTS (CARBON AND BORON FAMILY)
UNIT XII: ORGANIC CHEMISTRY-BASIC PRINCIPLES AND TECHNIQUES
UNIT XIII: HYDROCARBON
UNIT XIV: ENVIRONMENT CHEMISTRY

Law of Chemical Combination

The combination of elements to form compounds is governed by the following five basic laws.

(i) Law of Conservation of Mass

(ii) Law of Definite Proportions

(iii) Law of Multiple Proportions

(iv) Law of Gaseous Volume ( Gay Lussac’s Law)

(v) Avogadro’s Law

(i) Law of Conservation of Mass

This law was established by a French Chemist, A. Lavoisier. According to this law ” For any chemical change total mass of active reactants are always equal to the mass of the products formed.”

(ii) Law of Definite Proportions/ Law of Constant Composition

This law was proposed by Louis Proust in 1979. According to this law, ” A chemical compound always contains the same elements in definite proportion by mass and it does not depend upon the source of the compound.”

(iii) Law of Multiple Proportions

This law was proposed by Dalton in 1803. According to this law, ” When two elements combine to form two or more than two different compounds, then the different masses of one element, which combine with a fixed mass of the other, bear a simple ratio to one another.

(iv) Gay Lussac’s Law (1808)

According to this law, ” At given temperature and pressure the volumes of all gaseous reactants and products bear a simple whole-number ratio to each other.”

(v) Avogadro’s Law

This law was given by Avogadro in 1811. According to this law, ” equal volumes of gases at same temperature and pressure should contain an equal number of molecules. “

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