Acids Bases and Salts: Class 10 Science NCERT Chapter 2

Characteristics of NCERT Class 10 Chemistry Chapter 2 – Acids Bases and Salts 

In the previous chapter 1, you all learned about Chemical Reactions and Equations. In Chapter 2 of Class 10 NCERT chemistry, you will learn about Acids, Bases, and Salts and their composition.

Prologue to Acids, Bases, and Salts 

Classification of issue based on 

  1. a) synthesis – elements, compounds, and blends 
  2. b) state – solids, liquids, and gases 
  3. c) solvency – suspensions, colloids, and solutions 

Kinds of blends – homogeneous and heterogeneous 

Kinds of compounds – covalent and ionic 

Quick Revision notes 

Indicators: Indicators are substances that indicate the acidic or essential nature of the solution by the shading change. 

Kinds of Indicator:

There are numerous sorts of indicators. Some regular types of indicators are: 

  1. Common Indicators: Indicators acquired from familiar sources are called Natural Indicators. Litmus, turmeric, red cabbage, China rose, and so on are some regular common indicators utilized generally to show the acidic or basic character of substances. 

Litmus: Litmus is acquired from lichens. The solution of litmus is purple in shading. Litmus paper comes in two hues, blue and red. 

An acid turns blue litmus paper red. 

A base turns red litmus paper blue. 

Turmeric: Turmeric is another normal indicator. Turmeric is yellow in shading. Turmeric solution or paper turns reddish earthy colored with base. Turmeric doesn’t change shading when reacted with an acid. 

Red Cabbage: Red cabbage’s juice is red in colour and is initially purple in shading. The juice of red cabbage turns reddish with an acid and turns greenish when reacted with the base. 

  1. Olfactory Indicator: Substances whose smell changes when blended in with acid or base are known as Olfactory Indicators—for instance; Onion, vanilla, and so on. 

Onion: Paste or squeeze of onion loses its smell when included with base. It doesn’t change its smell with acid. 

Vanilla: The smell of vanilla disappears with base, yet its smell doesn’t evaporate with an acid. 

Olfactory Indicators are utilized to guarantee the support of outwardly disabled students in the lab. 

  1. Manufactured Indicator: Indicators combined in the lab are known as Synthetic Indicators—for instance, Phenolphthalein, methyl orange, and so forth. 

Phenolphthalein is a dull liquid. It stays boring with acid. However, it transforms into pink with a base. 

Methyl orange is initially orange in shading. It transforms into the red with acid and transforms into yellow with base. 

Indicator Original Colour Acid Base
Red litmus Red No Change Blue
Blue litmus Blue Red No change
Turmeric Yellow No Change Reddish brown
Red cabbage juice Purple Reddish Greenish yellow
Phenolphthalein Colourless Colourless Pink
Methyl Orange Orange Red Yellow
Onion n/a No change Smell vanishes
Vanilla n/a No change Smell vanishes

Acids : Acids are sharp in taste, turn blue litmus red, and dissolve in Water to deliver H+ particles. 

Model: Sulphuric acid (H2SO4), Acetic Acid (CH3COOH), Nitric Acid (HNO3), and so on. 

Properties of Acids: 

  • Acids have a sharp taste. 
  • Turns blue litmus red. 
  • The acid solution conducts electricity. 
  • Delivery H+ particles in aqueous solution. 

Sorts of Acids: Acids are divided into two kinds based on their event, i.e., Natural acids and Mineral acids. 

(I) Natural Acids: Acids that are gotten from normal sources are called Natural Acids or Organic Acids. 


Methanoic acid (HCOOH) 

Acetic acid (CH3COOH) 

Oxalic acid (C2H2O4), and so forth. 

Organic Acids and their Sources
Acids Sources
Acetic acid Vinegar
Ascorbic acid Guava, amla
Citric acid Lemon, orange and other citrus fruits
Lactic acid Sour milk, curd
Methanoic acid Ant sting, nettle sting
Oxalic acid Tomato
Tartaric acid Tamarind

(ii) Mineral Acids: Acids set up from minerals are known as Mineral Acids Example; Inorganic acids, man-made acids, or manufactured acid are otherwise called Mineral Acids. 


Hydrochloric acid (HCl) 

Sulphuric acid (H2SO4) 

Nitric acid (HNO3) 

Carbonic acid (H2CO3) 

Phosphoric acid (H3PO4), and so forth. 

Compound Properties of Acid: 

(I) The reaction of acids with metal: Acids give hydrogen gas alongside a particular salt when they respond with a metal. 

Metal + Acid → Salt + Hydrogen 


Hydrogen gas and zinc chloride are formed when hydrochloric acid responds with zinc metal. 

Hydrogen gas and sodium sulphate are framed when sulphuric acid responds with sodium metal. 

Test For Hydrogen Gas: The gas advanced after the reaction of an acid with metal can be tried by bringing a lit flame close to it, in the event that the gas bums with a pop stable, at that point it affirms the development of hydrogen gas. Igniting with pop stable is the trademark test for hydrogen gas. 

(ii) The reaction of acids with metal carbonate: Acids give carbon dioxide gas and individual salts alongside Water when they respond with metal carbonates. 

Metal carbonate + Acid → Salt + Carbon dioxide + Water 


HCL acid gives carbon dioxide gas, sodium chloride alongside Water when the response with sodium carbonate. 

Sulphuric acid gives calcium sulphate, carbon dioxide gas, calcium sulphate, and Water when it responds with CaCO3. 

HNO3 gives NaNO3, Water, and carbon dioxide gas when it responds with sodium carbonate. 

(iii)Acids’ reaction with hydrogen carbonates (bicarbonates): Acids give carbon dioxide gas, individual salt, and Water when they respond with metal HCO3. 

Metal hydrogen carbonate + Acid→ Salt + Carbon dioxide + Water 


Sulphuric acid gives sodium sulfate, Carbon dioxide gas, and Water when it responds with NaHCO3. 

Test For release of Carbon Dioxide Gas:Carbon dioxide turns lime Water smooth when gone through it. This is the trademark test for carbon dioxide gas. 

The gas advanced in light of the acid’s reaction with metal carbonate or metal hydrogen carbonate turns lime Water smooth. This shows that gas is carbon dioxide gas. This happens as a result of the development of a white precipitate of calcium carbonate. 

In any case, when an overabundance of carbon dioxide is gone through lime water, it causes a smooth shade of lime water to disappear. This happens on account of the development of Ca(HCO3)2. As it is soluble in water, consequently, the smooth shade of the solution blend disappears. 

Normal in Acids: Acids give hydrogen gas when they respond with metal. This shows all acids contain hydrogen. For instance; Hydrochloric acid (HCl), sulphuric acid (H2SO4), nitric acid (HNO3), and so on. 

At the point when an acid is dissolved in water, it dissociates hydrogen. The dissociation of hydrogen particles in aqueous solution is the regular property in all acids. Due to the dissociation of hydrogen particles in aqueous solution, an acid shows acidic conduct. 


Hydrochloric acid (HCl) gives hydrogen particle (H+) and chloride particle (Cl–) when it is dissolved in water. 

Acetic acid (CH3COOH) gives acetic acid derivation particles (CH3COO–) and hydrogen particle (H+). 


Strong Acids

An acid that is totally ionized in Water and delivers (H+) is called Strong Acid.

Weak Acids

An acid that is incompletely ionized in Water and in this way creates a modest quantity of hydrogen particles (H+) is known as a Weak Acid. 

Model: Acetic acid (CH3COOH), Carbonic acid (H2CO3) 

At the point when a concentrated solution of acid is diluted by blending Water, at that point, the grouping of Hydrogen particles (H+) or hydronium particles (H3O–) per unit volume diminishes. 

Bases: Bases are unpleasant in taste, have lathery touch, turn red litmus blue, and give hydroxide particles (OH–) in aqueous solution. 

Models: Sodium hydroxide (harsh pop) – NaOH 

Calcium hydroxide – Ca(OH)2 

Potassium hydroxide (scathing potash) – (KOH) 

Properties of Bases: 

  • Have a bitter taste. 
  • Lathery to contact. 
  • Turns red litmus blue. 
  • Behaviors electricity in solution. 
  • Delivery OH–particles in Aqueous Solution 

Kinds of bases: Bases can be divided into two sorts – Water soluble and Water-insoluble. 

The hydroxide of alkali and alkaline earth metals are soluble in water. These are otherwise called an alkali. 

For instance, sodium hydroxide, magnesium hydroxide, calcium hydroxide, and so forth. Alkali is viewed as a solid base. 

Compound properties of bases: 

(I) The reaction of Base with Metals: When alkali (base) responds with metal, it produces salt and hydrogen gas. 

Alkali + Metal → Salt + Hydrogen 

Models: Sodium hydroxide gives hydrogen gas and sodium zincate when the response with zinc metal. 

Sodium aluminate and hydrogen gas are shaped when sodium hydroxide responds with aluminum metal.

(ii) The reaction of Base with Oxides of Non-metals: Non-metal oxides are acidic in nature. For instance, carbon dioxide is a non-metal oxide. At the point when carbon dioxide is dissolved in water, it produces carbonic acid. 

Consequently, when a base responds with non-metal oxide, both neutralize each other coming about particular salt and Water. 

Base + Non-metal oxide → Salt + Water 

(Non-metal oxides are acidic in nature) 


NaOH gives Na2CO3 and Water when it responds with CO2. 

Ca(OH)2 gives calcium carbonate and Water when it responds with CO2. 

(iii) Neutralisation Reaction: A base is neutralized by an acid when they respond with one another, and certain salt and Water are framed. 

Acid + Base → Salt + Water 

Since acid and base reaction both neutralize one another, it is otherwise called Neutralization Reaction. 

Models: Sodium chloride and Water are framed when hydrochloric acid responds with sodium hydroxide (a solid base). 

Likewise, calcium chloride is framed alongside Water when hydrochloric acid responds with calcium hydroxide (a base). 

(iv) The reaction of Acid with Metal Oxides: Metal oxides are basic in nature. Consequently, when an acid responds with a metal oxide, both neutralize one another. In this reaction, the particular salt and Water are shaped. 

Acid + Metal Oxide → Salt + Water 

(Metal oxides are basic in nature)

Models: Calcium is metal. Along these lines, calcium oxide is a metallic oxide which is fundamental. At the point when an acid, for example, hydrochloric acid, responds with calcium oxide, a neutralization reaction happens, and calcium chloride, alongside the water, is framed. 

Also, when sulphuric acid responds with zinc oxide, zinc sulphate, and water are framed.

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