9
CBSE Marks
★★★★★
Difficulty
10
Topics
Very High
Board Weight
Topics Covered
10 key topics in this chapter
Properties of Acids & Bases
Acids & Bases in Water
Strength of Acid/Base Solutions
Importance of pH
pH Scale (0–14)
Salts: Formation & pH
Common Salt (NaCl)
Washing Soda & Baking Soda
Bleaching Powder
Plaster of Paris
Study Resources
Key Formulas & Reactions
| Formula / Reaction / Rule | Expression |
|---|---|
| pH Definition | \(pH = −log₁₀[H⁺]\) |
| Neutralisation | \(Acid + Base → Salt + Water\) |
| NaOH + HCl | \(NaOH + HCl → NaCl + H₂O\) |
| Washing Soda | \(Na₂CO₃·10H₂O\) |
| Baking Soda | \(NaHCO₃ (decomposes on heating → Na₂CO₃ + H₂O + CO₂)\) |
| Bleaching Powder | \(Ca(OCl)Cl (Cl₂ + Ca(OH)₂)\) |
| Plaster of Paris | \(CaSO₄·½H₂O (sets hard with water)\) |
| Chlor-alkali Process | \(2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂\) |
Important Points to Remember
Acids produce H⁺ (H₃O⁺) in water; bases produce OH⁻. pH < 7 is acidic, pH = 7 is neutral, pH > 7 is basic.
Neutralisation: Acid + Base → Salt + Water. The reaction is always exothermic.
Washing soda = Na₂CO₃·10H₂O; Baking soda = NaHCO₃; Bleaching powder = Ca(OCl)Cl; Plaster of Paris = CaSO₄·½H₂O.
The pH of blood (7.35–7.45) and soil must be maintained in a narrow range for biological function.