CHEMISTRY – MOLE CONCEPT
■ Premium Exam-Oriented Notes (100/100 Guarantee Level)
1. What is Mole Concept?
Mole concept is a counting system in chemistry, just like dozen in daily life. It connects atomic
mass, molecular mass, number of particles, and mass of a substance.
2. Mole Definition
One mole of any substance contains 6.022 × 10²³ particles (atoms, molecules, or ions). This
number is called Avogadro Number.
3. Important Formulae
1 Number of moles (n) = Given mass / Molar mass
2 Number of particles = n × Avogadro number
3 Mass = Number of moles × Molar mass
4 Volume of gas at STP = n × 22.4 L
4. Molar Mass
Molar mass is the mass of one mole of a substance expressed in g/mol. For compounds, it is the
sum of atomic masses of all atoms present.
5. Percentage Composition
Percentage of element = (Mass of element in compound / Molar mass of compound) × 100
6. Empirical & Molecular Formula
Empirical formula shows the simplest whole number ratio of atoms. Molecular formula shows the
actual number of atoms present.
7. Limiting Reagent
Limiting reagent is the reactant which gets completely consumed first and limits the amount of
product formed.
8. Concentration Terms
Term Formula
Molarity (M) Moles of solute / Volume of solution (L)
Molality (m) Moles of solute / Mass of solvent (kg)
Mole Fraction (χ) Moles of component / Total moles
9. Common Mistakes (Avoid These)
1 Using wrong molar mass
2 Forgetting unit conversion
3 Ignoring limiting reagent
■ Premium Exam-Oriented Notes (100/100 Guarantee Level)
1. What is Mole Concept?
Mole concept is a counting system in chemistry, just like dozen in daily life. It connects atomic
mass, molecular mass, number of particles, and mass of a substance.
2. Mole Definition
One mole of any substance contains 6.022 × 10²³ particles (atoms, molecules, or ions). This
number is called Avogadro Number.
3. Important Formulae
1 Number of moles (n) = Given mass / Molar mass
2 Number of particles = n × Avogadro number
3 Mass = Number of moles × Molar mass
4 Volume of gas at STP = n × 22.4 L
4. Molar Mass
Molar mass is the mass of one mole of a substance expressed in g/mol. For compounds, it is the
sum of atomic masses of all atoms present.
5. Percentage Composition
Percentage of element = (Mass of element in compound / Molar mass of compound) × 100
6. Empirical & Molecular Formula
Empirical formula shows the simplest whole number ratio of atoms. Molecular formula shows the
actual number of atoms present.
7. Limiting Reagent
Limiting reagent is the reactant which gets completely consumed first and limits the amount of
product formed.
8. Concentration Terms
Term Formula
Molarity (M) Moles of solute / Volume of solution (L)
Molality (m) Moles of solute / Mass of solvent (kg)
Mole Fraction (χ) Moles of component / Total moles
9. Common Mistakes (Avoid These)
1 Using wrong molar mass
2 Forgetting unit conversion
3 Ignoring limiting reagent
