L-9. Numericals Related to Mole | Examples 1 & 2 – Chapter 4 Stoichiometry | 9th Chemistry

Teacher: Prof. Majid ALI (Gold Medalist)
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Welcome to this detailed video on Numericals Related to Mole – Examples 1 & 2, from Chapter 4: Stoichiometry (9th Chemistry). In this lesson, we will work through:
📌 Balanced Chemical Equation:
CaCO₃ (s) + 2HCl (aq) → CaCl₂ (aq) + H₂O (l) + CO₂ (g)
Reactants → Products
1 mole CaCO₃ → 1 mole CaCl₂
2 moles HCl → 1 mole H₂O → 1 mole CO₂
100 g CaCO₃ → 111 g CaCl₂
73 g HCl → 18 g H₂O → 44 g CO₂
Example 1: Calculate mass of CaCl₂ formed
If 25 g of limestone (CaCO₃) reacts with excess HCl, how many grams of CaCl₂ will be produced?
Solution: 27.75 g of CaCl₂
Example 2: Moles of O₂ and CO₂ in combustion
When 1.80 moles of C₂H₅OH is burnt completely:
O₂ needed = 5.4 moles
CO₂ produced = 3.6 moles
We also apply the Law of Conservation of Mass, step-by-step mole conversions, and mole-to-mass relationships.
This video is perfect for Class 9 students preparing for exams, quizzes, or homework in chemistry.
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