NCERT Soluton for Class 10 Science Chapter 2 Acids Bases and Salts Free Download

NCERT Solution for Class 10 Science Chapter 2 Acids Bases and Salts Text Book Solution and Important QUeston MCQs and Notes Free Download PDF

Class 10 Science Chapter 2 Acid Bases and Salts Notes अम्ल, क्षार एवं लवण: लवण in Hindi

Acids | Class 10 Science Chapter 2

Acids is defined as the one which produces hydrogen ions in water. For Example, Sulphuric Acid, Hydrochloric Acid etc.

Arrhenius Concept: According to his way of judging substances, he classified the acids and bases as given below:
Acids are those that when dissolved in water, give hydrogen ion or we can write hydronium ion (H3O+)
This hydronium ion is formed due to the combination of hydrogen ion produced by acid with water molecule.

Classification Of Acids:

we have different classification based on different factors so let’s sum up and make ourselves familiar with it.

1. Depending upon source  from which they are obtained

• Organic acids
• Inorganic acids

Organic Acids are obtained from plants and animals  or we can say they are present in organic matter.

Example: in tomato, oxalic acid is present , in apple, malic acid and in lemon, we have citric acid and so many other acids are present in different organic substances.

Inorganic Acids are those that are obtained from minerals present in earth. These are quite reactive in nature. Example we have are : nitric acid, sulphuric acid, etc.

2. Classification of acids on the basis of strength

If we talk about strength, it means the amount of hydrogen ions given out when acid is dissolved in water.

On the basis of this we have two categories of acids –

• Strong acids
• Weak acids

Strong Acid is the acid that completely dissociates into hydrogen ion. These acids totally dissociate and leave no dissociated molecule of acid.

Example: Hydrochloric acid, sulphuric acid, etc. Weak Acid is the acid that partially dissociates into hydrogen ions. There actually
exists the equilibrium between dissociated ions and undissociated molecules of acids .

Example: Carbonic acid.

3. Classification of acids on the basis of water content

• Dilute acid
• Concentrated acid
• Dilute Acid is the acid that has more amount of water in it and less salt content.
• They are not quite strong.

Concentrated Acid is that which has less amount of water in it and more amount of salt content.

We can dilute the concentrated acid but need to take certain precautions as follows-

One can dilute concentrated acid by adding concentrated acid slowly in water with continuous stirring. By doing so, the heat released is comparatively less and is constantly absorbed by water. So, it prevents the reaction from becoming violent.

Bases | Class 10 Science Chapter 2

If we talk about bases, according to Arrhenius, they  are those that when dissolved in water give hydroxide ion (OH^–)

Example:

Calcium hydroxide Ca(OH)₂
Magnesium hydroxide Mg(OH)₂

Classification of bases:

1. Classification of bases on the basis of their solubility in water

The bases that are soluble in water are called alkalis.

Note : it is interesting to note that all bases are not alkalis but all alkalis are bases.

2. Classification on the basis of strength

• strong bases
• weak bases

Strong Bases: That completely dissociates in water to give hydroxide ions. These bases  totally dissociates and leave no dissociated molecule of base.

Example: Hydroxides of all reactive metals

Weak Bases: That do not completely dissociates in water to give hydroxide ions.

There actually exists the equilibrium between dissociated ions and undissociated molecules of bases.

Example: Calcium hydroxide etc.

Class 10 Science Chapters 2 Acids Bases and Salts

Physical Properties Of Acids And Bases

Some physical properties of acids are as follows –

1. They are sour.
2. They turn blue litmus red.
3. They are corrosive in nature

Some physical properties of bases are as follows –

1. They are bitter.
2. They turn red litmus blue.
3. They are soapy in nature

Chemical Properties of acids and bases

Chemical properties of acids

1. Action with Indicators: when treated with litmus, they turned blue litmus red.

2.Reaction with Metals: They react with acid to form metal salt and hydrogen gas
is released.

Acid +metal →metal salt + hydrogen gas

Example : HCl+Zn→ZnCl₂+H₂

3. Action with metal carbonate and metal bicarbonate

Whenever acids react with metal carbonate or metal bicarbonate, they form respective salts, water and carbon dioxide gas is released.

Example : acid + metal carbonate →metal salt + water + carbon dioxide gas

i.e. HCl +Na₂CO₃→NaCl +H₂O+CO₂

4. Reaction with Bases:

Acids react with bases to form salt and water.

i.e. Acid + base →salt and water

HCL+NaOH→NaCl+H₂O

This reaction is regarded as neutralization reaction as salt formed is neither acidic nor basic its neutral

5. All acids act as electrolytes in aqueous states

In aqueous state when current is passed they dissociate into ions . Chemical properties of bases

1.Action with Indicators: They turn red litmus blue
2. Reaction with Metals: They react with base to form oxy salt and hydrogen gas is released.

Example: Al+NaOH→NaAlO₂+H₂

3. Action with ammonium salts

Example: NH₄Cl+NaOH→NaCl+NH₄OH

4. Reaction with Acids:

Acid react with acids to form salt and water

Acid + base →salt and water

HCl+NaOH—-NaCl+H₂O

This reaction is regarded as neutralization reaction as salt formed is neither acidic nor basic its neutral

5. All bases act as electrolyte in aqueous states i.e. NaOH –> Na⁺ +OH^–

6. Salts are formed when acid and base react with each other.

i.e. acid + base→salt + water

HCl+NaOH→NaCl+H₂O

The salts are formed as a result of neutralization reaction as both acid and base neutralize each others effect.

The Nature of Salts Can Be-  Class 10 Science Chapter 2

1. Acidic Salts
2. Basic Salts
3. Neutral Salts

Acidic Salt

It is formed when strong acid react with weak base.

As the acid is strong, therefore, strong character is retained in the salt that is why it comes out to be acidic

Example : HCl+Ca(OH)₂ → CaCl₂+H₂O

Basic Salt

It is Formed When Strong Base Reacts With weak acid

Example : NaOH+CH₃COOH → CH₃COONa+H₂O

Neutral Salt

It is Formed When Weak Or Strong Acid And Base React With Each other. They Cancel Each Other’s Effect And Can Form Neutral Salt

Example : HCl+NaOH→NaCl+H₂O

• Ph and its biological importance, indicators Strength of acid and base is expressed in terms of pH
• It is the Logarithm of Reciprocal of Hydrogen ion Concentration.
• i.e.: pH =-LOG(H⁺)
• The ph of any substance can be detected by using ph paper or ph scale.
• pH scale consist of scale ranging from 0 to 14 .
• pH ranging from 0 to 7 are acids
• pH ranging from 7 to 14 are bases
• And 7 is neutral

For Measuring, We Have Ph Scale Given By: Observations Made On The Bases Of Ph Values Ph Range Indicate the strength of acids and bases as given below :

0-2	Strong Acid
2-4	Moderately Acidic
More Than 4:	Weak Acid
At 7:	Neutral
7-10:	Weak Base
10-12:	Moderately Basic
More Than 12:	Strongly Base

Effect of ph on dilution:

In Case Of Acids On Dilution:Ph Increases as acidic strength decreases
In Case Of Bases On Dilution: Ph Decreases as basic strength decreases

Importance of Ph | Class 10 Science Chapter 2

1. Biological Importance: Our Body Works Within 7-7.8 Ph. The Ph Of Acid Rain Is Below 5.6 And This Water Affects Aquatic Life.
2. Agriculture: Plants Also Specific Range Of Ph For Survival In Order To Grow Crops
3. In Dairies: Ph Value Of Milk Is Adjusted About 6.6. If Ph Falls Below 6.6 It Turns Sour.
4. In Tooth Decay: Tooth Decay Starts When Ph Of Mouth Falls Below 5.5. At That Ph Acid Reacts With Calcium Phosphate Of Tooth Enamel And Cause Its Corrosion. When We Eat Some Sugary Substance The Acids Production Is Stimulated That Corrode Enamel.

Indicators: Are the substances that bring about change in themselves when some acid or base is added to Natural and artificial indicators

Natural indicators: Litmus (it is extracted from lichens) original color of litmus is purple but in lab it is used as red and blue litmus.

• Effect of Acid: Turns blue litmus red
• Effect on Base: Turns red litmus blue
• Artificial Indicators: Phenolphthalein, methyl orange
• Effect on phenolphthalein-original colour is colourless
• Acid: Remain colourless
• Base: Turns pink
• Effect on methyl orange: original colour (orange)
• Acid: from orange to red
• Base:  from orange to yellow
• We have olfactory indicators as well that bring about a change in smell when any substance is added to it.

Like Onion Extract And Vanilla Extract

1. Effect Of Acid On Vanilla Extract: same smell
2. Effect Of Base On Vanilla Extract: smell changes
3. Effect Of Acid On Onion Extract: same smell
4. Effect Of Base On Onion Extract: smell changes

Class 10 Science Chapter 2 Acids Bases and Salts Related FAQ