In this article, we quick revise the chapter Acids, Bases and Salts of Class 10 Science CBSE
with pointwise cover all the topic
Acids, Bases and Salts Quick Revision Notes
1. An acid may be defined as a substance that releases H⁺ ions in an aqueous solution.
2. A base may be defined as a substance that releases OH
⁻
ions aqueous solution.
3. The nature of a solution whether acidic or basic can be determined with the help of indicators.
4. Indicators are organic dyes that may be natural or synthesized in the laboratory.
5. The common acid-base indicators are phenolphthalein, methyl orange and litmus.
6. The colour of litmus in neutral solution is purple, blue in the acidic solution and red in the basic solution.
7. Phenolphthalein is colourless in neutral and acidic solutions and pink alkaline solutions.
8. Methyl orange is orange in neutral and acidic solutions and yellow in basic solution.
9. Litmus is extracted from ‘lichen’ a plant belonging to a variety of Thallophyta. It is a natural indicator.
10. Methyl orange and phenolphthalein indicators are synthesised in the laboratory.
11. Onion, Vanilla and clove oil are olfactory indicators. They give different smells in acidic and basic solutions.
12. Dilute acids react with active metals to form metal salts and evolve hydrogen gas.
13. Metal oxides react with dilute acids to form salt and water.
14. Both metal carbonates and metal hydrogen carbonates evolve carbon-dioxide gas on reacting with dilute acids.
15. Upon passing carbon dioxide gas through lime water solution, it initially becomes milky and milkiness disappears after some time.
16. Basicity of an acid is the number of replaceable H atoms present in the acid.
17. The acidity of a base is the number of replaceable OH groups present in the base.
18. Metals like zinc, tin and aluminium react with caustic alkalies like NaOH or KOH to form metal salts and evolve hydrogen gas.
19. The relative strengths of acids and bases can be compared in terms of their degree of dissociation (𝜶).
20. Aqueous solutions of both acid and base conduct electricity due to the presence of ions.
21. Water helps in the dissociation of both acid and base into ions.
22. Acid and base react in an aqueous solution to form salt and water. The reaction is known as the neutralisation reaction.
23. An indicator helps in checking the completion of the neutralisation reaction.
24. The nature of solutions whether neutral, acidic or basic are expressed in terms of pH values.
25. The pH scale runs from 0 to 14. The pH of a neutral solution is 7, that of an acidic solution is less than this value and of basic strength.
26. Antacids help in neutralising acidity caused in the stomach due to the formation of excessive hydrochloric acid.
27. Normal salt is formed by the complete neutralisation of an acid by a base.
28. Acidic salts contain some replaceable hydrogen atoms while basic salts contain some replaceable hydroxyl groups.
29. Washing soda is chemically hydrated sodium carbonate (Na
₂
CO
₃•10
H
₂
O).
30. Baking powder consists of a mixture of baking soda (NaHCO
₃
) and tartaric acid (C
₄
H
₆
O
₆
).
31. Bleaching powder is chemically calcium oxychloride (CaOCl
₂
) and is formed by passing chlorine gas through dry slaked lime.
32. Chlorine released by bleaching powder helps in bleaching clothes.
33. The chemical formula of Plaster of Paris is CaSO₄
•
1/2H
₂
O.
34. Plaster of Paris is used for setting fractured bones.
35. Upon heating hydrated salts lose the molecules of water of crystallisation either partially or completely and may also undergo a change in colour