Overview of Acids and Bases Class 10 Notes | EduRev

Science Class 10

Class 10 : Overview of Acids and Bases Class 10 Notes | EduRev

The document Overview of Acids and Bases Class 10 Notes | EduRev is a part of the Class 10 Course Science Class 10.
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A wide variety of materials consists essentially of elements and compounds having different characteristics that exist around us. Some of them are sour, some are bitter, while some are salty in taste. 

Example: Sour and bitter tastes of food are due to acids and bases, respectively, present in them.

Acids react with bases to produce salt whose properties are different from acid and base.

Overview of Acids and Bases Class 10 Notes | EduRev

What are Acids?

The term "acid" is derived from the latin word "acidus" meaning sour to taste. Acids are defined as the one which produces hydrogen/Hydroxyl ions in water.
Example: Sulphuric Acid(H2SO4), Hydrochloric Acid (HCl) etc.

Properties of Acids:

  • Acids are sour in taste.
  • Acids turn blue litmus to red. This is used as a confirmation test for the presence of acid.
  • Acidic solutions can conduct electricity because they dissociate into ions which conduct electricity. 
  • Produce hydrogen(H+)/hydroxyl(H3O+) ions in water.
  • When acids react with metals, Hydrogen gas is evolved.
  • Acids are corrosive in nature.

According to Arrhenius: Those substances which give hydronium ion(H3O+) or Hion in their aqueous solution are called acids.

Note: Due to the corrosive nature acids are stored in glass and ceramic bottles.

Overview of Acids and Bases Class 10 Notes | EduRev


Try yourself: Which one will change from blue litmus to red?
View Solution


Chemical Properties of Acids 

  1. The Reaction of Acid with Metal
    Acid + Metal → Salt + Hydrogen gas
    Mg + H2SO4 → H2 + MgSO4
  2. The Reaction of Acid with Metal Carbonates
    Acids react with metal carbonates to form salt + water + CO2 gas↑:
    Na2CO3(s) + 2 HCl (aq) → 2NaCl(aq) + H2O (l) + CO2(g)The Reaction of Acid with Bicarbonates
    Acids react with metal bicarbonates to form salt + water + CO2 gas :
    NaHCO3 + HCl → NaCl + H2O + CO2The Reaction of Acids with Base (Neutralization reaction)
    Overview of Acids and Bases Class 10 Notes | EduRevOverview of Acids and Bases Class 10 Notes | EduRev
    Neutralisation Reaction

  3. The Reaction of Acid with Metal Oxide
    Salt and water are formed as metal oxides are basic in nature:
    Overview of Acids and Bases Class 10 Notes | EduRev

Try yourself:When an acid reacts with a metal, which one of the following gas is usually liberated?
 
View Solution


Classification of Acids
➢ On the Basis of Occurrence
(a) Mineral Acids (Inorganic Acids)
The acids which are usually obtained from minerals are known as Inorganic acids.
Overview of Acids and Bases Class 10 Notes | EduRev

Do You Know? 🤔
Aqua regia is also known as royal water because it can dissolve less reactive metals into it.

Example: Gold(Au) and Platinum(Pt)

Try yourself:Which of the following is used for dissolution of gold?
View Solution

(b) Organic Acids: Acids which are derived from plants and animals are known as Organic Acids. 
Example: Citric Acid from fruit

Overview of Acids and Bases Class 10 Notes | EduRevCitric Acid in Lemons

Table: Organic Acids
Overview of Acids and Bases Class 10 Notes | EduRev


➢ On the Basis of their Basicity
The basicity of an acid is the number of replaceable hydrogen atoms present in a molecule that can be produced by the complete ionisation of one molecule of that acid in an aqueous solution.

OR 

The basicity of an acid is determined by the number of hydronium ions (H3O+/H+(aq) produced per molecule of acid on ionisation.
(a) Monobasic Acids
The acid on complete ionisation produces one hydronium ion in aqueous solution.
Example:

  • Hydrochloric acid (HCl)
  • Nitric acid (HNO3)

  • Acetic acid (CH3COOH)

  • Formic acid (HCOOH)

Overview of Acids and Bases Class 10 Notes | EduRev
(b) Dibasic Acid
The acid on complete ionization produces two hydronium ions per molecule of acid in aqueous solution.
Example:
  • Sulphuric acid (H2SO4)
  • Carbonic acid (H2CO3)

Overview of Acids and Bases Class 10 Notes | EduRev

(c) Tribasic Acid
The acid on complete ionisation produces three hydronium ions per molecule of acid in aqueous solution.
Example:

  • Phosphoric acid (H3PO4)

Overview of Acids and Bases Class 10 Notes | EduRev

➢ Classification on the Basis of their Strength
(a) Strong Acid
The acid which undergoes complete ionisation in an aqueous solution is known as strong acids.
Example:

Overview of Acids and Bases Class 10 Notes | EduRevOverview of Acids and Bases Class 10 Notes | EduRev(b) Weak Acid
The acid which undergoes partial or incomplete ionization in aqueous solution is known as weak acids.
Overview of Acids and Bases Class 10 Notes | EduRevExample: 

  • Formic acid (HCOOH)
  • Oxalic acid (COOH)2
  • Carbonic acid (H2CO3)
  • Phosphoric acid (H3PO4)

➢ Classification on the Basis of Concentration of the Acid
(a) Concentrated Acid
The acids which contain a very small amount of water is called a concentrated acid.
(b) Dilute Acid

  • The acid which contains more amount of water is called a dilute acid. "Strength of an acid does not depend upon the concentration of an acid."

Important Fact
Aqua - Regia - Aqua regia is a mixture of (3 part HCl & 1 part HNO3) which dissolves even noble metals like Au(Gold), Pt(Platinum).

  • Strength of an Acid ∝ Concentration of hydronium ion

DilutionOverview of Acids and Bases Class 10 Notes | EduRev

Dilution of Acid
  • Dilution is the process of reducing the concentration of a solution by adding more solvent (usually water) to it.
  • It is a highly exothermic process.
  • To dilute acid, the acid must be added to water and not the other way round.

Try yourself:Which of the following acids is used as a food preservative?
View Solution


What are Bases?

Substances with a bitter taste and give a soapy touch are known as bases.

Example:

  • Sodium hydroxide (NaOH)
  • Zinc oxide (ZnO)
  • Copper oxide (CuO)
  • Calcium hydroxide [Ca(OH)2]
  • Magnesium hydroxide [Mg(OH)2]
  • Aluminium hydroxide [Al(OH)3]

Properties of Bases:

  • Bases produce hydroxide ions [OH] in H2O.
  • Water-soluble bases are called alkalies.
  • Bases are bitter in taste.
  • Bases turn Red Litmus blue.
  • Bases act as electrolytes in Solution.
  • Bases neutralize solutions containing H+ ions.
  • Bases have a slippery, ‘soapy’ feel.
  • Bases dissolve fatty material.
  • Strong bases are corrosive in nature.
    Example: NaOH, KOH

According to Arrhenius
"Those substances which give hydroxide or hydroxyl ion (OH-) in their aqueous solution" are called bases.

NaOH(aq.) → Na+(aq) + OH-(aq)
KOH(aq.) → K+(aq) + OH-(aq)

  • The compounds which are either metallic oxides or metallic hydroxides combine with acids to form salts and water only:
    CuO + 2HCl  →  CuCl2  +  H2O
    Base     Acid        Salt       Water
    NaOH  + HCl  →  NaCl  +  H2O
    Base       Acid         Salt       Water
    Mg (OH)2 + H2SO4 → MgSO4  + 2H2O
    Base            Acid          Salt          Water

Try yourself:What is the effect of the base on red litmus paper?
View Solution


What are Alkalis?

Bases that completely dissolve in water are called alkalis.
Examples:  KOH, NaOH, Ca(OH)2

All the alkalis are bases but all bases are not alkalis.

Examples: [Fe(OH)3] ferric hydroxide and cupric hydroxide [Cu(OH)2] are base, but not an alkali.

Chemical Properties of Bases

1. Reaction with Metals

  • Base reacts with active metals and produce hydrogen gas.
    Overview of Acids and Bases Class 10 Notes | EduRev

2. Reaction with Acids (Neutralization Reaction)

  • Base reacts with acids to form salts and water.
    Example: KOH + HCl → KCl + H2O

3. Reaction with Non-metallic Oxides

  • Base reacts with non-metallic oxides to form salts and water.
  • Base + Non metallic → salt + water
    Ca(OH)2 + CO2 → CaCO3 + H2O
    NaOH + CO2 → Na2CO3 + H2O
    Mg(OH)2 + CO2 → MgCO3 + H2O
Classification of Bases

➢  Classification on the basis of their Strength
(a) Strong alkalis or bases

  • The alkalis or bases which undergo almost complete ionisation in aqueous solution are known as strong alkalis or bases.
    Example:
    Overview of Acids and Bases Class 10 Notes | EduRev

(b) Weak alkalis or bases

  • The alkalis or bases which undergo only partial ionisation in aqueous solution are known as weak alkalis or Bases.
    Example:
    Overview of Acids and Bases Class 10 Notes | EduRev

➢ Classification on the basis of their Concentration
(a) Concentrated Base or Alkali

  • The bases or alkalis which contain a very small amount of water is called concentrated bases or alkalis.

(b) Dilute Base

  • The bases or alkali which contain more amount of water is called a dilute bases or alkalis
➢ Classification on the basis of their Acidity
  • The acidity of a base is determined by the number of hydroxyl (OH-) ions produced per molecule of a Base or Alkali on complete dissociation in water. 
"or"
  • The "number of hydrogen ions of an acid with which a molecule of that alkali or base react to produce salt and water is known as the acidity of an alkali or Base".

(a) Mono Acidic Bases or Alkali

  • The base or alkali on complete ionisation produces one hydroxyl (OH_) ion per molecule of the base in an aqueous solution.
    Example:
    NaOH (aq.) → Na+ (aq) + OH- (aq)

                                         Hydroxyl ion
    KOH(aq.) → K+ (aq) + OH- (aq)

                                       Hydroxyl ion

(b) Diacidic Bases (or alkalis)

  • The base or alkali on complete ionization produces two hydroxyl ion (OH-) per molecule of the base in an aqueous solution.
    Example:
    (i) Diacidic Bases
    Ca(OH)2(aq.) → Ca2+(aq.) + 2OH-(aq.)
    Mg(OH)2(aq.) → Mg2+(aq.) + 2OH-(aq.)
    (ii) Ferrous hydroxide [Fe(OH)2] and copper hydroxide [Cu(OH)2]
    Fe(OH)2(aq.) → Fe2+ + 2OH-(aq.)
    Fe+2(OH)2- + 2H+Cl-(aq.) → FeCl2 + 2H2O

(c) Tri Acidic Bases

  • The base or alkali on complete ionization produces three hydroxyl ion (OH)-  per molecule of the base in aqueous solution.
    Example: Aluminium hydroxide [Al(OH)3], Ferric hydroxide [Fe(OH)3]
    Al(OH)3(aq.) → Al3+(aq.) + 3OH-(aq.)
    Al3+(OH)3- + 3HCl(aq.) → AlCl3 + 3H2O

Table: Uses of BasesOverview of Acids and Bases Class 10 Notes | EduRev

Table: Comparison Between Properties of Acids & BasesOverview of Acids and Bases Class 10 Notes | EduRev


Frequently Asked Questions

Q 1. What types of ions are formed:
(a) When an acid is dissolved in water.
(b) When a base is dissolved in water?

When an acid is dissolved in water, it forms hydrogen or H+ ions whereas when a base is dissolved in water, it forms hydroxide or OH- ions.


Q 2. Name the acid along with its chemical formula present in ant sting.

The acid present in ant sting is methanoic acid (formic acid). The chemical formula is HCOOH.

Explanation: When an ant stings, it leaves formic acid (Methanoic acid) which causes pain and irritation. To get relief from the sting, a mild base like baking soda on the stung area gives relief.

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