1. Acids are sour to taste and turn blue litmus to red.
2. Bases are soapy to touch and turn red litmus to blue.
3. The natural materials like litmus, extract of red cabbage, turmeric solution and extracts of coloured petals of some flowers containing organic molecules, which are weak acids or bases, can be used as acid-base indicators to detect the nature of the solution for acidity or basicity. These are called natural acid-base indicators.
4. The synthetic materials such as methyl orange and phenolphthalein that can be used to test for acids and bases are called synthetic indicators.
5. Acids changed the orange colour of methyl orange indicator to red. Acids give colourless solution in phenolphthalein.
6. Bases changes the orange colour of the methyl orange solutions to yellow. Bases give pink colour in phenolphthalein.
7. Those substances whose odour changes in acidic or basic media are called olfactory indicator.
e.g.: Onion, Vanilla essence and Clove oil.
8. Acids liberate hydrogen gas by reacting with metals like Zn, Mg etc.
2 HCl + Zn →ZnCl2 + H2
(aq) (s) (aq) (g)
2 HCl + Mg → MgCl2 + H2
(aq) (s) (aq) (g)
9. Sodium hydroxide reacts with zinc metal to form sodium zincate and hydrogen gas.
2 NaOH + Zn → Na2ZnO2 + H2
10. The reaction of metal carbonates and hydrogen carbonates with acids gives corresponding salt, carbondioxide and water.
metal carbonate + acid → salt + carbondioxide + water
metal hydrogen carbonate + acid → salt + carbondioxide + water
11. On passing carbon dioxide through lime water. It changes to milky (white precipitate).
Ca(OH)2 + CO2 → CaCO3 ↓ + H2O
12. The reaction of an acid with a base to give a salt and water is known as a neutralisation reaction.
HCl + NaOH → NaCl + H2O
Acid + Base → Salt + Water
13. The substance present in antacid tablet is basic. Neutralisation reaction takes place in stomach when an antacid tablet is consumed.
14. Acids react with metallic oxides to form salt and water.
CuO + 2 HCl → CuCl2 + H2O
Metal oxide + Acid → Salt + Water
15. Bases react with non metallic oxides to form salt and water.
CO2 + Ca(OH)2 → CaCO3 + H2O
non metaloxide + base → Salt + Water
16. Aqueous solutions of acids conduct electricity due to presence of H+ ions.
17. In glucose and alcohol solution the bulb did not glow indicating the absence of H+ ions in these solutions.
18. Asubstance which produces H+ ions or H3O+ ions in aqueous solution is called an acid.
19. A substance which produces OH− ions in aqueous solution is called a base.
20. Bases which are soluble in water are called alkalis.
21. The process of dissolving an acid or a base in water is an exothermic process.
22. Mixing an acid or base with water result in decrease in the concentration of ions (H+/OH−) per unit volume. This process is called dilution and the acid or the base is said to be diluted.
23. The substance which gives large numbers of H+ ions in aqueous solution is called a strong acid.
24. The substance which gives less number of H+ ions in aqueous solution is called a weak acid.
e.g.: CH3COOH, H2CO3
25. The substance which gives large numbers of OH- ions in aqueous solution is called a strong base.
26. The substance which gives less number of OH- ions in aqueous solution is called a weak base.
27. Universal indicator is used to know the strength of acid or base.
28. Universal indicator is a mixture of several indicators.
29. Universal indicator shows different colours at different concentrations of hydrogen ions in a solution.
30. Sorensen introduced the pH scale to represent the H+ ion concentration in the solution.
31. A scale for measuring hydrogen ion concentration in a solution is called pH scale.
32. For acidic solution pH range is 0 to 7. For acidic solution pH < 7.
33. For basic solution the pH range is 7 to 14. For basic solution pH > 7.
34. For neutral solution, pH is equal to 7. For neutral solution pH = 7
e.g.: pH of distilled water is 7.
35. Living organisms can survive only in a narrow range of pH change.
36. If pH of rain water is less than 5.6. It is called acid rain.
37. When acid rain flows in to the rivers, it lowers the pH of the river water, the survival of aquatic life in such rivers becomes difficult.
38. Tooth decay starts when the pH of the mouth is lower than 5.5.
39. Tooth enamel is made of Calcium phosphate.
40. Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth.
41. Using tooth pastes, which are generally basic neutralise the excess acid and prevent tooth decay.
42. Our stomach produces hydrochloric acid and it helps in the digestion of food without harming the stomach.
43. During indigestion the stomach produces too much acid and this causes pain and irritation.
44. Antacids neutralise the excess acid in the stomach. Magnesium hydroxide or milk of magnesia is used as antacid.
45. Plants require a specific pH range for their healthy growth.
46. Honey bee sting leaves an acid which causes pain and irritation. Use of mild base like baking soda on the Honey bee are gives relief.
47. Stinging hair of leaves of nettle plant, inject methanoic acid causing burning pain. The leaf of the dock plant rubbing on the nettle plant stinging area gives relief.
48. An acid and a base react to form a salt.
49. Salt of a strong acid and a strong base in neutral and the pH value is 7.
e.g.: NaCl, KCl.
50. Salts of a strong acid and a weak base is acidic and the pH value is less than 7.
e.g.: NH4Cl, AlCl3
51. The salts of a weak acid and strong base are basic in nature and the pH value is more than 7.
e.g.: Na2CO3, NaHCO3
52. The salts of both weak acid and weak base nature depend on the relative strengths of acid and base.
53. Salts having the same positive or negative radicals belong to a family.
e.g.: NaCl and Na2SO4 belong to the family of sodium salts.
54. Sodium Chloride is known as table salt or common salt. sodium Chloride (NaCl) is used to enhance the taste of food.
55. Common salt is an important raw material for various materials of daily use, such as sodium hydroxide, baking soda, washing soda, bleaching powder and many more.
56. When electricity is passed through an aqueous solution of sodium chloride (brine) it decomposes to form sodium hydroxide, chlorine gas is obtained at the anode and hydrogen gas at the cathode.
2 NaCl + 2 H2O → 2 NaOH + Cl2 + H2
(aq) (l) (aq) (g) (g)
57. NaOH is used in decreasing metals, soaps detergents, paper making, artificials fibres etc.
58. Calcium oxy chloride (CaOCl2) is commonly known as bleaching powder.
59. Bleaching powder is obtained when chlorine gas is passed over dry slaked lime.
Ca(OH)2 + Cl2 → CaOCl2 + H2O
60. Uses of bleaching powder:
(i) It is used for bleaching cotton and linen in the textile industry for bleaching wood pulp in paper industry and for bleaching washed clothes in laundry.
(ii) Used as an oxidizing agent in many chemical industries
(iii) Used for disinfecting drinking water to make it free of germs.
(iv) Used as a reagent in the preparation of chloroform.
61. The chemical name of baking soda is sodium hydrogen carbonate of sodium bicarbonate (NaHCO3). Baking soda is a mild non corrosive base. The mixture of NaCl aqueous solution, ammonia and carbon dioxide is heated to form sodium hydrogen carbonate.
NaCl + H2O + CO2 + NH3 → NH4Cl + NaHCO3
63. Uses of Baking soda:
(i) Baking Powder mainly contains NaHCO3 and its other components are acidic Ca(H2PO4)2 and starch. NaHCO3 produces CO2 which rises through bubling the dough into smooth and spongy cake or bread.
NaHCO3 + H+ → CO2 + H2O + Na− (sodium salt of acid)
(ii) It is used as an antacid to remove excess acid in the stomach.
(iii) It is used as fire extinguisher.
(iv) It acts as mild antiseptic
64. The formula of washing soda is Na2CO3.10 H2O.
65. Sodium Carbonate can be obtained by heating baking soda.
2 NaHCO3 → Na2CO3 + CO2 + H2O
66. Recrystallisation of sodium carbonate gives washing soda.
Na2CO3 + 10 H2O → Na2CO3 . 10 H3O
67. Uses of washing soda:
(i) Sodium carbonate (washing soda) is used in glass, soap and paper industries.
(ii) It is used in the manufacturing of sodium compounds such as borax.
(iii) Sodium carbonate can be used as a cleaning agent for domestic purposes.
(iv) It is used for removing permanent hard ness of water.
68. Water of crystallization is the fixed number of water molecules present in one formula unit of a salt.
69. Chemical formula for hydrated copper sulphate is CuSO4. 5 H2O
70. Examples of hydrated salts are
(i) Washing soda Na2CO3 . 10 H2O
(ii) Gypsum CaSO4 . 2 H2O
71. The colour of hydrated copper sulphate is blue and it is heated to convert into white.
72. Calcium sulphate hemi hydrate (CaSO4. H2O) is called Plaster of paris.
73. Gypsum is heated at 373 k to form Plaster of paris. Plaster of paris is a white powder.
74. Plaster of paris is used as plaster for supporting fractured bones in the right position.
75. Plaster of paris on mixing with water, it sets in to hard solid mass due to the formation of gypsum.
CaSO4. H2O + 1 H2O → CaSO4. 2 H2O
Plaster of paris Gypsum
76. Plaster of paris is used for making statues, moulds, black board chalks, toys, materials for decoration and for making surfaces smooth.
Conceptual flow Chart