Class 10 Science Chapter 2 Notes Acids, Bases and Salts

ACIDS:

These are the substances which have sour taste.
They turn blue litmus solution red.
They give H⁺ ions in aqueous solution.
The term ‘acid’ has been derived from the Latin word, acidus, which means sour.

Strong Acids: HCI, H₂SO₄, HNO₃
Weak Acids: CH₃COOH, Oxalic acid, Lactic acid
Concentrated Acid: Having more amount of acid + less amount of water
Dilute Acid: Having more amount of water + less amount of acid

BASES:

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 [NaOH, KOH, Ca(OH)₂].

SALTS:
These are the compounds formed from reaction of acid and base.
Example: NaCl, KCI.

INDICATORS:
These are the substances which change their colour/smell in different types of substances.

Chemical Properties of Acids and Bases

Reaction of Metal with Acids

Acid + Metal → Salt + Hydrogen Gas

e.g., 2HCl + Zn → ZnCl₂ + H₂

* Hydrogen gas released can be tested by bringing burning candle near gas bubbles, it burns with pop sound.

Reaction of Metal with Bases

Base + Metal → Salt + Hydrogen Gas

2NaOH + Zn → Na₂ZnO₂ + H₂

* Na₂ZnO₂ → Sodium Zincate

Reaction of Metal Carbonates/Metal Hydrogen Carbonates with Acids

Acid + Metal Carbonates/Metal Hydrogen Carbonates → Salt + CO₂+ H₂O

e.g., 2HCl + Na₂CO₃ → 2NaCl + CO₂ + H₂O
HCl + NaHCO₃→ NaCl + CO₂+ H₂O

* CO₂ can be tested by passing it through lime water.
Ca(OH)₂+ CO₂ → CaCO₃+ H₂O (Lime water turns milky.)

CaCO₃ → Insoluble

When excess * CO₂ is passed,
CaCO₃ + CO₂ + H₂O → Ca(HCO₃)₂ (Milkiness disappears.)

Ca(HCO₃)₂ → Soluble

Reaction of Metal Carbonates/Metal Hydrogen Carbonates with Acids

Base + Metal Carbonates/Metal Hydrogen Carbonates → No Reaction

Reaction of Acids and Bases With Each Other

Acid + Base → Salt + H₂O

Neutralisation Reaction: Reaction of acid with base to give salt and water is called as neutralisation reaction.

E.g., HCl + NaOH → NaCl + H₂O

Strong Acid + Weak Base → Acidic salt + H₂O [pH of the Solution is less than 7]
Weak Acid + Strong Base → Basic salt + H₂O [pH of the Solution is more than 7]
Strong Acid + Strong Base → Neutral salt + H₂O [pH of the Solution is = 7]
Weak Acid + Weak Base → Neutral salt + H₂O [pH of the Solution is = 7]

Reaction of Metallic Oxides with Acids
Metallic oxides + Acid → Salt + Water
* Metallic oxides are basic in nature. because it reacts with acid and forms salt and water.

E.g., CaO, MgO are basic oxides.
Metallic Oxide + Acid → Salt + H₂O
CaO + 2HCl → CaCl₂ + H₂O

Reaction of a Non-metallic Oxide with Base

* Non-metallic oxides are acidic in nature.
Non-metallic Oxide +Base → Salt+H₂O
CO₂+Ca(OH)₂ → CaCO₃+ H₂O

What do all Acids and Bases have in common

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.

Class 10 Science Chapter 2 Notes Acids, Bases and Salts

Class 10 science notes