The document discusses acids, bases and salts. It defines acids as substances that have a sour taste and turn litmus paper red, while bases have a bitter taste and soapy texture and turn litmus paper blue. Examples of common acids include citric acid in lemons and lactic acid in curd. The document also covers the reactions of acids and bases, such as acids reacting with metals to produce salts and hydrogen gas. A neutralization reaction occurs when an acid and base react and form water and a salt.

1. Acids, Bases and Salts
CLASS 10 SCIENCE – Chapter 2
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MG SCHOOL SCIENCE

2. Tastes of some common edible substances :-
Edible substances have different tastes. Some have sour taste, some have bitter taste, some have
sweet taste and some have salty taste.
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SI No Substance Taste
1 Lemon juice sour
2 Orange juice Sour/sweet
3 Vinegar Sour
4 Curd Sour
5 Tamarind Sour
6 Sugar Sweet
7 Common salt Salty
8 Amla Sour
9 Baking soda Bitter
10 Grapes Sour/sweet
11 Unripe mango Sour
12 glucose Sweet
Chapter 2 Acids, Bases and Salts

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Acids
Acids are substances which have sour taste. These substances are acidic in nature.
SI No Substance Name of acid
1 Vinegar Acetic acid
2 Ants sting Formic acid
3 Citrus fruits like lemon, orange
etc.
Citric acid
4 Curd Lactic acid
5 Spinach Oxalic acid
6 Amla Ascorbic aicd
7 Tamarin, grapes, unripe
mangoes etc.
Tartaric acid
Chapter 2 Acids, Bases and Salts

4. Bases are substances which have bitter taste and have a soapy touch. Theses substances are
basic nature.
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Bases
SI No substance Name of base
1 Lime water Calcium hydroxide
2 Window cleaner Ammonium hydroxide
3 Soap Sodium hydroxide
potassium hydroxide
4 Milk of magnesia Magnesium hydroxide
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Chapter 2 Acids, Bases and Salts

5. Substances which are neither acidic nor basic are called neutral substances.
Ex: sugar solution, salt solution, distilled water etc.
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Neutral substances
Substances which change their color in acidic and basic solutions are called indicators.
Ex: litmus, turmeric, China rose petals are some naturally occurring indicators.
Indicators
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litmus paper turmeric China rose
Chapter 2 Acids, Bases and Salts

6. 1. Natural indicators
2. Synthetic indicators
3. Olfactory indicators
Natural indicators: Found in nature in plants.
Examples: Litmus, red cabbage leaves extract, flowers of hydrangea plant, turmeric.
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Types of Indicators and its properties
red cabbage leaves
turmeric flowers of hydrangea
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Chapter 2 Acids, Bases and Salts

7. Litmus as indicator
• Litmus is a natural indicator obtained from lichens. It is available in the form of
solution as blue litmus solution and red litmus solution or as strips of paper as
blue litmus paper and red litmus solution.
• In distilled water its color is purple. In acidic solution it turns red and in basic
solution it turns blue.
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Natural indicators
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lichens
litmus paper
Chapter 2 Acids, Bases and Salts

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Synthetic indicators: These are chemical substances.
Examples: Methyl orange, phenolphthalein.
Types of Indicators and its properties
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Chapter 2 Acids, Bases and Salts

9. 9
Types of Indicators and its properties
Olfactory indicators: These substances have different odour in acid and bases.
Vanilla extract
onion
Clove oil
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Chapter 2 Acids, Bases and Salts

10. • The term 'acid' has been derived from the Latin word, 'acidus' which means sour.
• Acids have sour taste.
• They turn blue litmus solution red.
• They give H+ ions in aqueous solution.
Strong Acids: HCI, H2S04 , HNO3
Weak Acids: CH3COOH, Oxalic acid, Lactic acid
Concentrated Acids: More amount of acid + Less amount of water
Dilute Acids: More amount of water + Less amount of acid
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Properties of Acids
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Chapter 2 Acids, Bases and Salts

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• These are the substances which are bitter in taste and soapy in touch.
• They turn red litmus solution blue.
• They give OH- ions in aqueous solution.
Strong Bases: NaOH, KOH, Ca(OH)2
Weak Bases: NH4OH
Alkalis: These are bases which are soluble in water.
Examples: NaOH, KOH, Ca(OH)2.
Properties of Acids
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Chapter 2 Acids, Bases and Salts

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Reaction of Acids with Metals:
Acids react with metal to form metal salt and releases Hydrogen Gas.
Acid + Metal → Salt + Hydrogen Gas
Example: Zinc granules react with dilute Hydrochloric acid in a test tube.
2HCl + Zn → ZnCl2 + H2
Hydrogen gas released can be tested by bringing burning candle near gas bubbles, it burst with pop sound.
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Chapter 2 Acids, Bases and Salts

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Bases react with metal to evolve hydrogen Gas. Also, note that all metals
do not react with bases. The metal must be more reactive than the metals
present in the base for the reaction to take place.
Base + Metal → Salt + Hydrogen gas
Example: Zinc granules react with NaOH solution to form sodium zincate
and evolve hydrogen gas.
2NaOH + Zn → Na2ZnO2 + H2
Reaction of Base with Metals:
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Chapter 2 Acids, Bases and Salts

14. Acids reacts with Metal Carbonates and Metal Hydrogen carbonates to form Salt, Carbon dioxide and
water.
Metal carbonate/Metal hydrogen carbonate + Acid → Salt + Carbon dioxide + Water
Examples:
(i) 2HCl + Na2CO3 → 2NaCl + CO2 + H2O
(ii) HCl + NaHCO3 → NaCl + CO2 + H2O
CO2 can be tested by passing it through lime water. It turns
lime water milky.
Ca(OH)2 + CO2 → CaCO3 + H2O
When excess CO2 is passed, milkiness disappears.
CaCO3 + CO2 + H2O → Ca(HCO)3
➢Bases do not react with Metal Carbonates and Metal Hydrogen carbonates.
Base + Metal Carbonate/Metal Hydrogen Carbonate → No Reaction
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Reaction of Acids with Metal Carbonates and Metal Hydrogen carbonates
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Chapter 2 Acids, Bases and Salts

15. Acids and Bases react to form salt and water.
Acid + Base → Salt + Water
Neutralization Reaction: Reaction of acid with a base is called as neutralization reaction.
Example: HCl + NaOH → NaCl + H2O
Strong Acid + Weak Base → Acidic salt + H2O
Weak Acid + Strong Base → Basic salt + H2O
Strong Acid + Strong Base → Neutral salt + H2O
Weak Acid + Weak Base → Neutral salt + H2O
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Reaction of Acids and Bases with each other
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Chapter 2 Acids, Bases and Salts

16. Metallic oxides are basic in nature.
Example: CaO, MgO are basic oxides.
Metallic Oxide + Acid → Salt + H2O
CaO + 2HCl → CaCl2 + H2O
Non-metallic oxides are acidic in nature.
Non-metallic Oxide + Base → Salt + H2O
CO2 + Ca(OH)2 → CaCO3 + H2O
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Reaction of Metallic Oxides with Acids
Reaction of Non-Metallic Oxides with bases
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Chapter 2 Acids, Bases and Salts

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(i) Acid + Metal Carbonate → Salt + CO2 + Water
(ii) Acid + Metal → Salt + H2
(iii) Acid + Metal Hydrogen Carbonate → Salt + CO2 + H2O
(iv) Acid + Metallic oxide → Salt +H2O
(v) Acid + Base → Salt + H2O
(i) Base + Metal → Salt + H2
(ii) Base + Metal Carbonate → No Reaction
(iii) Base + Metal Hydrogen Carbonate → No Reaction
(iv) Base + Acid → Salt + H2O
(v) Base + Non Metallic oxide → Salt + H2O
Reaction of Acid
Reaction Of Base
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Chapter 2 Acids, Bases and Salts

18. • All acids have H+ ions in common.
• Acids produce H+ ions in solution which are responsible for their acidic properties.
• All bases have OH- (hydroxyl ions) in common
• Acids produce H+ ions in presence of water.
• H+ ions cannot exist alone, they exist as H3O+ (hydronium ions).
• H+ + H2O → H3O+
• HCl + H2O → H3O+ + Cl-
• Bases when dissolved in water gives OH− ions.
• NaOH + H2O → OH- + Na+
• Bases soluble in water are called alkali.
Note: While diluting acids, it is recommended that the acid should be added to water and not water to acid
because the process of dissolving a acid or a base in water is highly exothermic.
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Similarities between all Acids and all Bases
Acid or Base in Water Solution
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Chapter 2 Acids, Bases and Salts

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• Strength of acid or base can be estimated using universal indicator.
• Universal indicator: It is a mixture of several indicators. It shows different colours at
different concentrations of H+ ions in the solution.
• pH Scale: A scale for measuring H+ ion concentration in a solution. p in pH stands for
‘potenz’ a German word which means power.
• If value of ph is equal to 7 → neutral solution
• If value of pH is less than 7 → acidic solution
• If value of pH more than 7 → basic solution
Strength of Acids and Base solutions
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Chapter 2 Acids, Bases and Salts

20. Organic Acids and their Sources
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Vinegar Acetic acid
Curd Lactic acid
Oranges Citric acid
Lemons Citric acid
Tamarind Tartaric acid
Ant sting Formic acid
Apples Malic acid
tomotoes Oxalic acid
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Chapter 2 Acids, Bases and Salts