Acids Bases and Salts — Karnataka (SSLC) Class 10 Science Solutions (Free)

Acids: sour taste, turn blue litmus red, pH < 7 (HCl, H2SO4). Bases: bitter taste, slippery, turn red litmus blue, pH > 7 (NaOH, NH3). Salts: formed by neutralization of acid + base, neutral taste, pH = 7 (NaCl, CaCO3). Chemical formula: Acid + Base = Salt + Water.

pH = measure of acidity/alkalinity based on H+ ion concentration. Scale: 0-14. Acids: pH < 7 (e.g., vinegar pH 3, lemon juice pH 2). Neutral: pH = 7 (pure water, NaCl solution). Bases: pH > 7 (e.g., baking soda pH 8.3, bleach pH 13). Higher pH = more basic; lower pH = more acidic.

HCl + NaOH = NaCl + H2O. Products: salt (NaCl) + water. In this reaction, H+ ions from acid combine with OH- ions from base to form water molecules. The salt formed (NaCl) is neutral and soluble. This is called complete neutralization when both reactants are in stoichiometric proportion.

Indicators are substances that change color in acidic or basic solutions. Three natural indicators: 1) Litmus (red in acid, blue in base). 2) Turmeric (yellow in base, reddish-brown in acid). 3) Phenolphthalein (colorless in acid, pink in base). These help identify if a substance is acidic, basic, or neutral.

Strong acids completely ionize in water, releasing all H+ ions (HCl, H2SO4, HNO3). Weak acids partially ionize; only some molecules release H+ (acetic acid in vinegar, citric acid in lemon). Strong acids conduct electricity better and have lower pH than weak acids of same concentration. Weak acids are reversible: CH3COOH ⇌ CH3COO- + H+.