Class 10 Science Chapter 2: Acids, Bases and Salts – NCERT Solutions Notes Acids, Bases and Salts is an important chemistry chapter in Class 10 Science. It explains the nature of acids and bases, their properties, reactions, and the formation of salts. This chapter is frequently asked in exams in both conceptual and numerical forms. These notes are structured for clear understanding and quick revision. Key Concepts Acids Acids are substances that release hydrogen ions (H⁺) in aqueous solution. Examples: HCl (Hydrochloric acid), H₂SO₄ (Sulphuric acid), CH₃COOH (Acetic acid) Properties: Sour taste Turns blue litmus red Reacts with metals to produce hydrogen gas Bases Bases are substances that release hydroxide ions (OH⁻) in aqueous solution. Examples: NaOH, KOH, Ca(OH)₂ Properties: Bitter taste Soapy touch Turns red litmus blue Indicators Indicators are substances that change colour in acidic or basic solutions. Examples: Litmus Phenolphthalein Methyl orange Strength of Acids and Bases Strength depends on the amount of ions produced in water. Strong acid: HCl, H₂SO₄ Weak acid: CH₃COOH Strong base: NaOH Weak base: NH₄OH pH Scale The pH scale measures acidity or basicity of a solution. pH < 7 → Acidic pH = 7 → Neutral pH > 7 → Basic Lower pH means stronger acid, higher pH means stronger base. Important Reactions Reaction with Metals Acid + Metal → Salt + Hydrogen gas Example: Zn + 2HCl → ZnCl₂ + H₂ Reaction with Metal Carbonates Acid + Carbonate → Salt + Water + CO₂ Example: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ Neutralization Reaction Acid + Base → Salt + Water Example: HCl + NaOH → NaCl + H₂O Salts Salts are formed when acids and bases react. Types of Salts Neutral salts (NaCl) Acidic salts Basic salts Important Compounds Common Salt (NaCl) Used in food and industry. Baking Soda (NaHCO₃) Used in baking and as an antacid. Washing Soda (Na₂CO₃·10H₂O) Used in cleaning and glass making. Plaster of Paris (CaSO₄·½H₂O) Used in medical casts and moulds. Water of Crystallization Water molecules present in crystalline salts. Example: CuSO₄·5H₂O (blue vitriol) NCERT Important Questions (Concept Based) Why does dry HCl gas not change dry litmus paper? Because ions are formed only in aqueous solution. Why is pH important in our body? It helps maintain biological processes and enzyme activity. What happens when acid reacts with metal? Hydrogen gas is released along with salt formation. Important Diagrams to Revise pH scale chart Lab setup for acid-base reaction Structure of salt crystals Why this chapter is important This chapter forms the base of chemical understanding in higher classes. It is frequently asked in exams in: pH-based questions Reactions Salt identification Conceptual reasoning Final Revision Tip Focus on: pH scale and its applications Important reactions Common salts and their uses NCERT back exercises