Acid bases salts

• Acid turns blue litmus colour to red
• Base turns red litmus colour to blue
• Bases soluble in water are called alkalis, examples include KOH and Mg(OH)2
• Turmeric is a natural indicator
• Reaction of acid with metals: In most cases, metals replace hydrogen from acids
• Metal oxide + Acid → Salt + Water
• Reaction of base with metals: 2NaOH + Zn → Na2ZnO2 (sodium zincate) + H2
• Acids with metal carbonate and hydrogen carbonate: Carbonate + Acid → Salt + Water + CO2
• Passing carbon dioxide gas evolved through lime water: Ca(OH)2 + CO2 → CaCO3 + H2O
• Acid-Base reaction: Acid + Base → Salt + Water
• In water solution: Acid → H+ ion; H+ + H2O → H3O+; Base → OH- ion
• Higher H+ concentration → Strong acid; Lower H+ concentration → Weak acid
• Higher the OH- concentration → Stronger the base
• pH Measure: pH → Measure of acidity → Measure H+ concentration on the scale (0 - 14)
• pH 7 → Neutral solution; pH < 7 → Acidic solution; pH > 7 → Basic solution
• Salts' pH = 7; Human body pH = 7.0 - 7.8
• Change in pH in body causes: Tooth decay, stomach pain, burning pain (Honey bee sting)
• Plants and animals are sensitive to pH change
• Self-defense by animals and plants through chemical warfare
• Common salt: NaCl; Bleaching powder: CaOCl2
• Preparation of Bleaching powder: Ca(OH)2 + Cl2 → CaOCl2 + H2O; Use: Oxidising agent, Disinfecting material
• Baking soda (NaHCO3): Preparation and Use - Making baking powder (Baking soda + Mild acid, like tartaric acid), Ingredient for antacids, Soda-acid fire extinguisher
• Washing soda: Na2CO3.10H2O; Preparation and Use - In glass, soap, paper industries, Making sodium compounds such as borax, As domestic cleaning agent
• Removing permanent hardness of water
• Water of crystallisation: Fixed number of water molecules present in one formula unit of salt; Example - In gypsum, the water of crystallisation is 2
• Hydrated substances: Substances containing water of crystallisation, for example, hydrated copper sulphate (CuSO4.5H2O)
• Anhydrous substances: Substances either not containing water of crystallisation or from which water of crystallisation is removed, for example, sodium chloride (NaCl) and anhydrous copper sulphate (CuSO4)
• Drying agents: Substances that absorb moisture without undergoing a chemical reaction, for example, anhydrous calcium chloride (CaCl2)
• Dehydrating agents: Substances that remove chemically bonded water from a compound, for example, concentrated sulphuric acid (H2SO4)