Acids,Bases and Salts

1. Lesson-2 Acids and Bases

2. 1. Chemical properties of acids and Bases 2. What do the acids and Bases have in common 3. How strong are acids or Base solutions 4. Salts

3. Litmus Test Acids change BLUE litmus to RED Bases change RED litmus to BLUE Olfactory indicators Onion and vanila essencce No smell in base buttheir charecteristic smell in acid

4. Reaction with Metals Acids + Metals Salt + hydrogen gas Zn + H2SO4 ZnSO4+ H2 H2 gas burns with a POP sound

5. Reaction with Metal carbonates Acid+Metal Carbonates Salt +CO2+H2O Na2CO3 + 2HCl 2NaCl +CO2 + H2O Sodium carbonate

6. Reaction with Metal hydrogen carbonates Acid+Metal hydrogen Carbonates Salt +CO2+H2O NaHCO3 + HCl NaCl +CO2 + H2O Sodium hydrogen carbonate

7. Action of acids with base Acid + Base Salt + Water HCl + NaOH NaCl + H2O Neutralization reaction

8. Action of acids with metal oxides Metal oxide + Acids Salt + Water CuO(s) + 2HCl CuCl2 +H2O Copper (II) oxide Copper(II) Chloride (Black) (Blue-green) Neutralisation reaction Milk of Magnesia BACK

9. What do Acids and Bases have in common Acids dissociates on dissolving to produce Hydrogen ions H➕ Bases dissociates on dissolving in water to produce hydroxide ions OH➖

10. Strong Acids: An acid which is completely ionised in water and thus produce a large amount of hydrogen ion is called a strong acid. Weak Acids : An acid which is partially ionised in water and thus produces a small amount of hydrogen ions is called a weak acid.

11. Most bases do not dissolve in water but some bases dissolve in water. The bases that dissolve in water are called alkali. Strong base : A base which is completely ionised in water is called a strong base. Weak Acids : A base which is partially ionised in water is called a weak base. BACK

12. Strength of an acid and base: pH Scale The pH of a solution is inversely proportional to the concentration of hydrogen ions.

13. Importance of pH in everyday Life pH of our Digestive System: The pH is 1.4 Tooth decay starts when pH of the mouth falls below 5.5 Bee sting is acidic Wasp sting is basic BACK

14. Salts Salts are formed when acids reacts with bases. The first part of the name of salt is derived from the name of base and the second part of the name of the salt comes from the name of the acid. Example: Sodium chloride. Base- Sodium hydroxide Acid- Hydrochloric acid Base- Sodium hydroxide Acid - Hydrochloric acid

15. Salt Family Sulphuric acid Sulphates Nitric Acid Nitrates Carbonic acid Carbonates Acetic acid Acetates

16. Solutions of salts also conduct electricity. pH of Salt Solution Strong acid and strong base Neutral Strong acid and weak base acidic Weak acid and Strong base basic

17. Common Salt[Sodium chloride- NaCl] ● Common salt is obtained from seawater-through evaporation of sea-water. ● Salt from underground deposits-rocksalt NaOH + HCl NaCl + H2O (caustic soda)

18. Chemicals from common salt ● Sodium hydroxide {Caustic soda } NaOH ● Calcium oxychloride { Bleaching powder} CaCl2 ● Sodium hydrogen carbonate {Baking soda } NaHCO3 ● Sodium carbonate decahydrate {Washing soda } Na2CO3.10H2O

19. Caustic soda: Electrolysis of brine[aqueous solution of salt ] NaCl(aq) + H2O NaOH (aq) + Cl2 +H2

20. Bleaching powder: Ca(OH)2 + Cl2 CaOCl2 + H2O (dry slaked lime) (bleaching powder) Uses ● Bleaching in textile industries ● For bleaching in paper factories ● Disinfecting drinking water

21. Baking soda: NaCl + NH3 +H2O +CO2 NaHCO3 + NH4Cl (Baking soda) Uses ● Tasty crispy pakoras ● Faster the cooking ● For making baking powder{baking soda+tartaric acid} ● Used as antacid ● Soda acid fire extinguisher

22. Plaster of Paris [ CaSO4.½H2O] CaSO4.2H2O CaSO4.½H2O + 1½H2O (Gypsum) ( Plaster of Paris) Water of crystallisation The water molecules which form part of the structure of a crystal are called water of crystallisation.