Strong and weak acids and bases

1. Ionisation of Acids and Bases

• Acids and bases ionise in water to form ions.
• The extent of ionisation determines whether they are strong or weak.

2. Characteristics of Strong and Weak Acids

Strong Acids	Weak Acids
Completely ionise in water	Partially ionise in water
High $[H_3O^+]$	Low $[H_3O^+]$
Low pH (closer to 1)	Higher pH (closer to 7)
Good electrical conductors	Poor electrical conductors
High reaction rate	Low reaction rate
Example: $HCl, HNO₃, H₂SO₄$	Example: $CH₃COOH, H₂CO₃, H₃PO₄$

3. Characteristics of Strong and Weak Bases

Strong Bases	Weak Bases
Completely dissociate in water	Partially ionise in water
High $[OH^-]$	Low $[OH^-]$
High pH (closer to 14)	Lower pH (closer to 7)
Good electrical conductors	Poor electrical conductors
Example: $NaOH, KOH$	Example: $NH₃, Ca(OH)₂$

4. Understanding pH and Conductivity

• pH indicates acidity or basicity:
  • $pH < 7 → Acidic$
  • $pH = 7 → Neutral$
  • $pH > 7 → Basic$
• Electrical conductivity depends on ion concentration:
  • More ions → Higher conductivity
  • Fewer ions → Lower conductivity

5. Key Takeaways

• Strong acids and bases ionise completely, producing more ions and having higher conductivity.
• Weak acids and bases ionise partially, producing fewer ions and having lower conductivity.
• Reaction rate and pH can be used to classify acids and bases in chemical reactions.