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.
All you need of Class 10 at this link: Class 10

INTRODUCTION
A wide variety of materials consists essentially of elements and compounds having different characteristics exist around us. Some of them are sour, some are bitter, while some are salty in taste. 

Overview of Acids and Bases Class 10 Notes | EduRevExample: 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.

ACIDS
The term "acid" is derived from the latin word "acidus" meaning sour to taste.

  • Acids is defined as the one which produces hydrogen/Hydroxyl ions in water.
    Example: Sulphuric Acid, Hydrochloric Acid etc.

  • Acids are sour in taste.

  • Acids turn blue litmus to red. This is used as confirmation test for the presence of acid.

  • Acidic solutions can conduct electricity because they dissociate into ions which conduct electricity. 

  • When acids react with metals, Hydrogen gas is evolved.

  • Acids are corrosive in nature.
    NOTE: Due to the corrosive nature acids are stored in glass and ceramic bottles.
    Overview of Acids and Bases Class 10 Notes | EduRev

According to Arrhenius theory An acid is a substance which on dissolving in water dissociates into H+ ions.
Overview of Acids and Bases Class 10 Notes | EduRev
Note: Hydrogen ion do not exist as H+ ions in solution, they attach themselves to the polar water molecules to form hydronium ions or hydroxonium ions, H3O+ or H+(aq) make correct representation of H3O+ and H+
Overview of Acids and Bases Class 10 Notes | EduRev

Overview of Acids and Bases Class 10 Notes | EduRev

Overview of Acids and Bases Class 10 Notes | EduRev

Chemical properties of acids 
1. Reaction of Acid with Metal:
Acid +   Metal     → Salt + Hydrogen gas
Mg    + H2SO4    →  H2 +   MgSO4

2. 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)

3. Reaction of Acid with Bicarbonates:
Acids react with metal bicarbonates to form salt + water + CO2 gas 
NaHCO3 + HCl → NaCl + H2O + CO2

4. Reaction of acids with base (Neutralization reaction):
Overview of Acids and Bases Class 10 Notes | EduRev

5. Reaction of acid with metal oxide:
Salt and water is formed as metal oxides are basic in nature.
Overview of Acids and Bases Class 10 Notes | EduRev

CLASSIFICATION OF ACIDS 
(1) On the basis of occurrence
(i) 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 and platinum.

(ii) Organic Acids: Acids which are derived from plants and animals are known as Organic Acids. 
For example: Citric Acid from fruit.

Overview of Acids and Bases Class 10 Notes | EduRevFig: Citric acid example of organic acids

The acids which are usually obtained from plants and animals are known as organic acids.

NameWhere found or used
Formic acid (HCOOH)Found in the stings of ants and bees, used in tanning leather, in medicines for treating gout.
Acetic acid (CH3COOH)Found in vinegar, used as solvent in the manufacture of dyes and perfumes.
Lactic acidResponsible for sourcing of milk in curd
Benzoic acidUsed as a food preservative
Citric acidPresent in lemon, orange and citrus fruits
Tartaric acidPresent in tamarind.


(2) 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 aqueous solution."
or "Basicity of an acid is determined by number of hydronium ions (H3O+/H+(aq) produced per molecule of acid on ionisation."
(i) Monobasic Acids
The acid on complete ionisation produce one hydronium ion in aqueous solution.
Example- 

Hydrochloric acid (HCl)
Hydrobromic acid (HBr)
Hydrofluoric acid (HF)
Hydroiodic acid (HI)
Nitric acid (HNO3)
Acetic acid (CH3COOH)
Formic acid (HCOOH)

Overview of Acids and Bases Class 10 Notes | EduRev

(ii) 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

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

Overview of Acids and Bases Class 10 Notes | EduRev

(3) Classification on the basis of their strength
(i) Strong Acid
The acid which undergoes complete ionisation in aqueous solution is known as strong acids.
Example-

Overview of Acids and Bases Class 10 Notes | EduRev
(ii) 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 | EduRev
Example- Formic acid (HCOOH)
Oxalic acid (COOH)2
Carbonic acid (H2CO3)
Phosphoric acid (H3PO4)

(4) Classification on the basis of concentration of the Acid
(i) Concentrated Acid
The acids which contains a very small amount of water is called a concentrated acid.
(ii) Dilute Acid       

Overview of Acids and Bases Class 10 Notes | EduRevFig: Dilution of acidThe acids which contain 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, Pt.

Strength of an Acid ∝ Concentration of hydronium ion.
BASES
Substances with bitter taste and give a soapy touch are known as bases.

Properties of Bases:

  • Produce hydroxide ions [OH] in H2O.
  • Water soluble bases are called alkalies.
  • Bitter Taste
  • Turn Red Litmus blue.
  • Act as electrolytes in Solution.
  • Neutralize solutions containing H+ ions.
  • Have a slippery, ‘soapy’ feel.
  • 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)
Example

Sodium hydroxide (NaOH)
Zinc oxide (ZnO)
Copper oxide (CuO)
Calcium hydroxide [Ca(OH)2]
Aluminum hydroxide [Al(OH)3]

The compounds which are either metallic oxides or metallic hydroxides. Which combines 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

Alkalis: Bases which completely dissolves 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 base
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
For Example,
KOH + HCl → KCl + H2O

3. Reaction with Non-metallic Oxides
Base reacts with non-metallic oxides to form salt 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
(1) Classification on the basis of their strength
(i) Strong alkalis or bases
The alkalis or bases which undergo almost complete ionisation in aqueous solution are known as strong alkalis or bases.
Examples-
Overview of Acids and Bases Class 10 Notes | EduRev
(ii) 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

(2) Classification on the basis of their concentration
(i) Concentrated Base or Alkali
The bases or alkalis which contain a very small amount of water is called concentrated bases or alkalis.
(ii) Dilute Base
The bases or alkali which contain more amount of water is called a dilute bases or alkalis

(3) Classification on the basis of their acidity

Overview of Acids and Bases Class 10 Notes | EduRevFig: Soaps are basic in natureAcidity 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 acidity of an alkali or Base".
(i) Mono acidic Bases or Alkali
The base or alkali on complete ionisation produces one hydroxyl (OH_) ion per molecule of base in aqueous solution.
Example-
NaOH (aq.) → Na+ (aq) + OH- (aq)
                                       Hydroxyl ion
KOH(aq.) → K+ (aq) + OH- (aq)
                                      Hydroxyl ion

(ii) Diacidic Bases (or alkalis)
The base or alkali on complete ionization produce two hydroxyl ion (OH-) per molecule of base in aqueous solution
Example-
(A) Diacidic Bases of
Ca(OH)2(aq.) → Ca2+(aq.) + 2OH-(aq.)
Mg(OH)2(aq.) → Mg2+(aq.) + 2OH-(aq.)
(B) Diacidic Bases
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

(iii) Tri Acidic Bases
The base or alkali on complete ionization produces three hydroxyl ion (OH)-  per molecule of 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

USES of Bases

Overview of Acids and Bases Class 10 Notes | EduRev

Comparison Between Properties of ACIDS & BASES
Overview of Acids and Bases Class 10 Notes | EduRev

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