Lecture Notes: Upcoming Board Examinations and Basic Chemistry

Motivation and Exam Preparation

• Motivational Quote: मुस्कुराए हमेशा छुपाए हैं गम तुम्हें वक्त बताया कौन है हम
  • Encouragement for students facing stress and demotivation due to upcoming board exams
• Attendance: Students asked to mark their attendance and like the stream
• Schedule: Physics completed, chemistry chapter to follow
• Materials Provided: Premium lecture, notes on Telegram, booklets for practice questions

Chapter Overview: Acids and Bases

Introduction to Acids

• Definition: Acid is a hydrogen-containing substance capable of donating a proton.
• Practical Example: H2SO4, HNO3
• Properties:
  • Turns blue litmus red
  • Strong acids are very reactive
  • Lactic acid in muscles causes cramps

Introduction to Bases

• Definition: Chemical substances with a bitter taste that turn red litmus blue
• Examples: NaOH, KOH, Ca(OH)2
• Properties:
  • Releases OH- ions in water

Alkalis

• Definition: Bases that are soluble in water
• Examples: NaOH, KOH

Salts

• Formation: Produced when acids and bases react (e.g., NaCl)
• Types: Acidic salts, basic salts

Common Chemical Reactions

• Acid + Metal: Produces salt + hydrogen gas
  • Example: Zn + H2SO4 → ZnSO4 + H2
• Acid + Metal Oxide: Produces salt + water
  • Example: CuO + HCl → CuCl2 + H2O
• Acid + Metal Carbonate: Produces salt + water + CO2
  • Example: Na2CO3 + HCl → NaCl + H2O + CO2
• Non-Metallic Oxide + Base: Produces salt + water
  • Example: CO2 + Ca(OH)2 → CaCO3 + H2O

Commonalities Between Acids and Bases

• Both are electrolytes
• Acids release H+ in water while bases release OH-

Dilution of Acids and Bases

• Definition: Adding water to lower concentration
• Strong vs Weak Acids/Bases: Degree of ionization in water

pH Scale

• Range: 1 to 14, indicates acidity or basicity
  • 7 = Neutral
  • <7 = Acidic

  • 7 = Basic

• Importance: Daily life examples (e.g., stomach acid is very acidic with a pH of 1)

Indicators

• Types: Litmus paper, phenolphthalein, methyl orange
• Function: Indicates whether a substance is acidic or basic
• Examples:
  • Turmeric turns red in basic solution
  • Phenolphthalein turns pink in basic solution
  • Methyl orange turns red in acidic solution

Universal Indicator

• Indicates both nature and strength (e.g., pH paper)

Important Chemical Compounds

Sodium Hydroxide (NaOH)

• Formed from brine solution
• Uses: Soap making, paper making, artificial fibers

Hydrochloric Acid (HCl)

• Uses: Cleaning steel, making ammonium chloride

Bleaching Powder (Ca(OCl)₂)

• Formed by reacting Ca(OH)₂ with Cl₂
• Uses: Disinfecting water, bleaching cotton

Baking Soda and Washing Soda

• Baking Soda (NaHCO₃): Form from brine solution with NH₃ and CO₂
  • Uses: Antacid, baking
• Washing Soda (Na₂CO₃ · 10H₂O): Formed by heating baking soda
  • Uses: Removing hardness of water

Plaster of Paris (CaSO₄ · 1/2H₂O)

• Formed by heating gypsum
• Uses: Making casts, fire protection systems