Lesson (2) - Chemistry - Senior 2

Unit 1: Chemical Calculations

Lecture 1: Mole Concept

Instructor: Dr. Mahmoud Badr

Introduction

In this lecture we explore the concept of the mole—how chemists count particles by grouping them into moles, and why the mole is fundamental to relating microscopic particles to macroscopic masses in chemical reactions.

Part 1: Mole Definition

The mole is defined as the amount of substance containing exactly 6.022 × 10²³ elementary entities (atoms, molecules, ions, etc.). It provides a bridge between particle count and mass. The number is known as Avogadro’s number. :contentReference[oaicite:0]{index=0}

Part 2: Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is numerically equal to the atomic or molecular mass when using standard atomic weights. :contentReference[oaicite:1]{index=1}

Applications & Examples

Example calculations: converting mass to moles (n = m / M), computing molar mass for compounds (sum of atomic masses), and applying mole concept in reaction stoichiometry to predict amounts of products and reactants.

Conclusion

Mastery of the mole and molar mass is essential for all chemical calculations. In upcoming lessons, you will use these concepts to solve problems in reactions, concentrations, and quantitative chemistry.