Pg:- 102, 103. Ch:- 5

• Mole is the SI unit of the amount of substance.

• One mole is 6.022 * 10^23

• The molar mass of a substance is the mass of one mole of that substance, expressed in grams per mole (g/mol). For example, the molar mass of water (H2O) is approximately 18.02 g/mol.

• To find the number of moles we use the formula n= m/M. m is the mass of the sample and M is the molar mass of the substance.

Importance of the Mole Concept

1. Chemical Reactions: The mole concept allows chemists to relate quantities of reactants and products in a chemical reaction. Balanced chemical equations provide the mole ratio of reactants and products, which can be used to calculate the amounts needed or produced.

2. Stoichiometry: The mole concept is essential for stoichiometry, which is the calculation of reactants and products in chemical reactions. It ensures that equations are balanced and helps in predicting the amounts of substances consumed and produced.

3. Understanding Properties: By understanding the number of particles in a given amount of substance, chemists can better comprehend the properties of materials, such as their reactivity, phase behavior, and physical properties.