Skip to main content
General Awareness 3% exam weight

Chemical Reactions — Acids, Bases and Salts

Part of the UPPSC PCS study roadmap. General Awareness topic genera-002 of General Awareness.

→ See in Roadmap Build 1-Month Plan

Chemical Reactions — Acids, Bases and Salts

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

Acids, Bases and Salts — Key Facts for UPPSC PCS Core concept: Acids release H⁺ ions (pH < 7), bases release OH⁻ ions (pH > 7), and salts are formed by neutralisation reactions High-yield point: pH scale (0–14), common indicators (litmus, phenolphthalein), and important salts (NaCl, Na₂CO₃, NaHCO₃) are frequently tested ⚡ Exam tip: Memorise pH of common substances (lemon juice ~2, blood ~7.4, bleach ~13) and uses of key salts in daily life

🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

Chemical Reactions — Acids, Bases and Salts — UPPSC PCS Study Guide Overview: Understanding acid-base chemistry is essential for UPPSC PCS General Science Core principles:

  • Acids: pH < 7, sour taste, turn blue litmus red; examples — HCl (hydrochloric), H₂SO₄ (sulphuric), CH₃COOH (acetic/vinegar)
  • Bases: pH > 7, bitter taste, slippery feel, turn red litmus blue; examples — NaOH, Ca(OH)₂, NH₄OH
  • Neutralisation: Acid + Base → Salt + Water; e.g., HCl + NaOH → NaCl + H₂O
  • Salts: Common salts and uses — washing soda (Na₂CO₃), baking soda (NaHCO₃), bleaching powder (CaOCl₂)
  • Indicators: Litmus (red/blue), turmeric, phenolphthalein, methyl orange

Key points: Difference between strong and weak acids, pH of everyday substances, reactions of metals with acids Study strategy: Memorise pH values and salt names first, then practise chemical equations

🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

Chemical Reactions — Acids, Bases and Salts — Comprehensive UPPSC PCS Notes Full coverage: Acid-base chemistry for UPPSC PCS General Science preparation

Theories of Acids and Bases:

  • Arrhenius theory: Acids ionise to give H⁺; bases ionise to give OH⁻
  • Brønsted–Lowry theory: Acids are proton donors; bases are proton acceptors
  • Lewis theory: Acids are electron-pair acceptors; bases are electron-pair donors

pH Scale and Indicators:

  • pH = –log[H⁺]; pure water has pH 7 (neutral at 25°C)
  • pH < 7 → acidic; pH > 7 → basic/alkaline
  • Natural indicators: litmus (lichen), turmeric (yellow in acid, red in base), red cabbage juice

Important Reactions:

  • Metal + Acid → Salt + Hydrogen gas (e.g., Zn + H₂SO₄ → ZnSO₄ + H₂↑)
  • Metal oxide + Acid → Salt + Water (base–acid reaction)
  • Non-metal oxide + Base → Salt + Water
  • Neutralisation: acid + base → salt + water

Key Salts and Industrial Uses:

  • NaCl (common salt): food preservation, raw material for Cl₂, NaOH
  • Na₂CO₃ (washing soda): cleaning agent, glass/soap manufacture
  • NaHCO₃ (baking soda): baking, fire extinguishers, antacid
  • CaOCl₂ (bleaching powder): disinfection of water, bleaching textiles
  • Na₂SO₄·10H₂O (Glauber’s salt): laxative, paper industry

Common Mistakes to Avoid: Confusing washing soda with baking soda; mixing up strong/weak acids with concentrated/dilute acids Practice: Attempt previous year UPPSC PCS questions on acids, bases, pH, and salt uses

Content adapted based on your selected roadmap duration. Switch tiers using the selector above.