The Mole Concept - IGCSE Chemistry
Presented by Jasveer Singh Mehta
⚛️ What is a Mole?
• 1 mole = 6.022 × 10²³ particles (Avogadro's Number)
• A counting unit for atoms, molecules, ions.
• Makes it easier to work with very small particles.
⚛️ Why Use Moles?
• Atoms are tiny and hard to count individually.
• The mole is a bridge between atoms and grams.
• It helps in stoichiometric calculations.
⚖️ Relative Atomic Mass (Ar) and Moles
• Ar = average mass of an atom compared to 1/12 of carbon-12.
• 1 mole of an element = Ar in grams.
• Example: 1 mole of carbon = 12g.
📘 Mole Formula
Moles = Mass (g) ÷ Mr (g/mol)
Mr = Sum of relative atomic masses of elements in a compound.
🧮 Example Calculations
1. Moles in 18g of H₂O: Mr = 18 → 18/18 = 1 mole
2. Mass of 2 moles of CO₂: Mr = 44 → 2 × 44 = 88g
🧮 Moles and Particles
Particles = Moles × 6.022 × 10²³
Use to find atoms, ions, molecules in a sample.
📘 Empirical Formula from Mass
1. Divide each mass by Ar
2. Divide all by the smallest value
3. Get whole number ratio → Empirical Formula
Example: 12g C, 4g H → CH₄
🎈 Molar Gas Volume
• At room temp & pressure (rtp): 1 mole = 24 dm³
• Volume = Moles × 24
• Use for reactions involving gases
❓ Recap + Quiz
✔ What is a mole?
✔ Key formulas: Moles = Mass ÷ Mr
✔ Gas volume, particles, empirical formula
Mini Quiz:
1. How many particles in 2 moles?
2. Mass of 3 moles of NaCl (Mr = 58.5)?
🙏 Thank You
Any questions?
Presented by: Jasveer Singh Mehta