Learn Chapter 2, Acids Bases and Salts of Science, Class X, NCERT, CBSE

1. sb
Science
Class – X
NCERT

2. 2.1 Acids and Bases
• Acid in food
– Sour taste
• Base in food
– Bitter taste
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Chapter 2 - Acids, Bases and Salts

3. 2.1 Acids and Bases
• Examples of Acids:-
– Hydrochloric Acid [HCl]
– Sulphuric Acid [H2SO4]
– Nitric Acid [HNO3]
– Acetic Acid [CH3COOH]
• Examples of Bases:-
– Sodium Hydroxide [NaOH]
– Calcium Hydroxide [Ca(OH)2]
– Potassium Hydroxide [KOH]
– Magnesium Hydroxide [Mg(OH)2]
– Ammonium Hydroxide [NH4OH]
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Chapter 2 - Acids, Bases and Salts

4. 2.1 Acids and Bases
• 2.1.1 Detection of Acids and Bases:-
– Visual indicators:-
• On adding these indicators to acids or bases, their
colour changes.
• Red Litmus paper
• Blue Litmus paper
• Phenolphthalein solution
• Methyl-orange solution
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Chapter 2 - Acids, Bases and Salts

5. 2.1 Acids and Bases
• 2.1.1 Detection of Acids and Bases:-
– Olfactory indicators:-
• On adding these indicators to acids or bases, their
odour changes.
• Onion
• Dilute vanilla essence
• Clove oil
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Chapter 2 - Acids, Bases and Salts

6. 2.1 Acids and Bases
• 2.1.2 Reaction with Metals:-
– Acids:-
• Hydrogen atoms are displaced by metal to form a
compound called salt.
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Chapter 2 - Acids, Bases and Salts

7. 2.1 Acids and Bases
• 2.1.2 Reaction with Metals:-
– Bases:-
• As in acids, Hydrogen (H2) is released in the reaction of
metals with bases to form salt.
(However, all metals do not show such behaviour)
Hydrogen
gas
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Chapter 2 - Acids, Bases and Salts

8. 2.1 Acids and Bases
• 2.1.3 Reaction with Metal Carbonates and
Metal Hydrogencarbonates:-
– Acids:-
• Salt, water and Carbon-di-oxide are produced.
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Chapter 2 - Acids, Bases and Salts

9. 2.1 Acids and Bases
• 2.1.3 Reaction with Metal Carbonates and
Metal Hydrogencarbonates:-
– Bases:-
• Metal Carbonates and Metal Hydrogencarbonates do
not react with bases, as they themselves are bases.
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Chapter 2 - Acids, Bases and Salts

10. 2.1 Acids and Bases
• 2.1.4 Reaction with each other:-
– Salt and water are produced.
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Chapter 2 - Acids, Bases and Salts

11. 2.1 Acids and Bases
• 2.1.5 Reaction of Metal oxide with Acids:-
– Salt and water are produced.
– Since,
– Metal oxides are considered to be Basic in nature.
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Chapter 2 - Acids, Bases and Salts

12. 2.1 Acids and Bases
• 2.1.5 Reaction of Non-metallic oxide with
Base:-
– Salt and water are produced.
– i.e., Base + Non-Metallic oxide  Salt + Water
– Since, Base + Acid  Salt + Water
– Thus, Non-metallic oxides can be considered as
Acids.
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Chapter 2 - Acids, Bases and Salts

13. 2.2 Characterstics of Acids and Bases
• Neutralization reaction:-
– Acid and Base, when react with each other,
neutralize each other producing Salt and Water.
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Chapter 2 - Acids, Bases and Salts

14. • 2.2.1 Dissolving of Acid or Base with water:-
– Acids:-
• Produce Hydrogen ions, H+(aq) or H3O+, in water
solution.
– Bases:-
• Produce Hydroxide ions, OH- (aq), in water solution.
• Water soluble Bases are called Alkalis.
2.2 Characterstics of Acids and Bases
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Chapter 2 - Acids, Bases and Salts

15. • 2.2.1 Dissolving of Acid or Base with water:-
– is an Exothermic process.
– decreases the concentration of ions (H3O+ or OH– )
per unit volume resulting in dilution of the acid or
base.
2.2 Characterstics of Acids and Bases
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Chapter 2 - Acids, Bases and Salts

16. • pH scale (potenz or power of Hydrogen scale)
– Higher the Hydrogen ion concentration, lower is
the pH value.
• 0 = highly acidic
• 7 = neutral solution
• 14 = highly alkaline/basic
– Measurement of pH:-
• Universal indicator (a mixture of several indicators)
itself or paper impregnated with the universal
indicator (pH paper) is used.
2.3 Strength of Acid or Base
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Chapter 2 - Acids, Bases and Salts

17. • Levels/Values of pH scale
2.3 Strength of Acid or Base
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Chapter 2 - Acids, Bases and Salts

18. • 2.3.1 Value/Importance of pH:-
– Human body pH = 7.0 to 7.8
– Acid rain pH < 5.6
– Stomach pH is Acidic
– Antacids (which cure stomach acidity) pH is Basic
– During tooth decay mouth pH < 5.5
– Bee-sting and stinging hair of nettle plant are
acidic
– Mild base like baking soda on the stung area gives
relief in pain
2.3 Strength of Acid or Base
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Chapter 2 - Acids, Bases and Salts

19. • 2.3.1 Value/Importance of pH:-
– Naturally occuring acids:-
2.3 Strength of Acid or Base
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Chapter 2 - Acids, Bases and Salts

20. • Examples:-
– Potassium sulphate [K2SO4]
– Sodium sulphate [Na2SO4]
– Calcium sulphate [CaSO4]
– Magnesium sulphate [MgSO4]
– Copper sulphate [CuSO4]
– Sodium chloride [NaCl]
– Sodium nitrate [NaNO3]
– Sodium carbonate [Na2CO3]
– Ammonium chloride [NH4Cl]
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

21. • 2.4.1 Families of salts:-
– Salts having the same positive or negative radicals
are said to belong to a family.
– Example:-
• NaCl and Na2SO4 belong to the family of sodium salts.
• NaCl and KCl belong to the family of chloride salts.
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

22. • 2.4.2 pH of salts:-
– Strong acid + strong base salt of pH = 7
– Strong acid + weak base  salt of pH < 7
– Weak acid + strong base  salt of pH > 7
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

23. • 2.4.3 Common salt (Sodium Chloride, NaCl):-
– Hydrochloric acid (HCl) + Sodium hydroxide (NaOH)
gives common salt and water.
– Found dissolved in sea water along with other
salts.
– Also found as deposits of solid salts at various
places in the form of crystals. Brown coloured due
to impurities. Formed from dried up seas.
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

24. • 2.4.3 Chemicals from Common Salt:-
– Used as raw material for making:-
• Sodium hydroxide [NaOH]
• Baking soda [NaHCO3]
• Washing soda [Na2CO3.10H2O]
• Bleaching powder [CaOCl2]
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

25. • 2.4.3 Chemicals from Common Salt:-
– Sodium hydroxide [NaOH] production through chlor-alkli
process:-
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

26. • 2.4.3 Chemicals from Common Salt:-
– Production of Bleaching power [CaOCl2]:-
• Chlorine (Cl2) produced in the chlor-alkali process is
used for making bleaching powder.
– Uses of Bleaching powder:-
• Bleaching cotton and linen textiles.
• Beaching wood pulp in paper factory.
• Oxidising agent in chemical industries.
• Making drinking water free of germs.
2.4 Salts
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Chapter 2 - Acids, Bases and Salts
Dry slaked
lime

27. • 2.4.3 Chemicals from Common Salt:-
– Production of Baking soda (Sodium
hydrogencarbonate) [NaHCO3]:-
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

28. • 2.4.3 Chemicals from Common Salt:-
– Uses of Baking soda (Sodium hydrogencarbonate)
[NaHCO3]:-
• Making of baking powder by mixing it with a mild edible
acid like tartaric acid.
– CO2 produced during the reaction causes bread to rise making
it soft and spongy.
• Ingredient of Antacid. Gives relief in stomach acidity.
• Used in soda-acid fire extinguishers. CO2 and H2O help
extinguish the fire.
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

29. • 2.4.3 Chemicals from Common Salt:-
– Production of Washing soda [Na2CO3.10H2O]:-
• Sodium Chloride as produced by heating baking soda is
recrystalised to form washing soda. Basic pH.
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

30. • 2.4.3 Chemicals from Common Salt:-
– Uses of Washing soda[Na2CO3.10H2O]:-
• Sodium Carbonate (washing soda) is used in glass soap
and paper industries.
• Manufacture of sodium compounds such as Borax.
• Cleaning agent for domestic purposes.
• Removing permanent hardness of water.
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

31. • 2.4.3 Crystaline salts:-
– Copper Sulphate [CuSO4.5H2O]
– Sodium Carbonate [Na2CO3.10H2O] (washing soda)
– Calcium Sulphate [CaSO4.2H2O] (gypsum)
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

32. • 2.4.3 Crystaline salts:-
– Plaster of Paris:-
• On heating Calcium Sulphate [CaSO4.2H2O] at 373 K, it
becomes Calcium Sulphate Hemihydrate [CaSO4.½H2O].
• Two units of CaSO4 share one molecule of H2O.
• It is used by doctors for supporting fractured bones in
right position. On mixing it with water, it changes to
gypsum again giving a hard solid mass.
2.4 Salts
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Chapter 2 - Acids, Bases and Salts

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