Acid Bases Salts | Class 10th Science | CBSE Notes | Study World | Part 1

Acid Bases Salts || 10 Science || CBSE Notes || Part 1

Dear Students, Today we are going to share the Notes of Acid  Bases and Salts Notes. These notes are prepared by the experienced teachers. These notes are free to all the students. These notes has been prepared according to the CCE pattern of school education based on NCERT
Syllabus prescribed by the Central Board of School Education for Class X. All the important topics are covered in these notes. We are regularly update these notes as per the syllabus. 

CBSE Class 10 Science Acids Bases and Salts Notes

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Some Important Topics

·  Acid Bases Salts

·  Indicators

¨ Litmus

¨ Methyl orange

¨ Phenolphthalein

¨ Olfactory Indicator

·  Acid

¨ Organic acid

¨ Strong Acid

¨ Weak Acid

¨ Concentrated acid

¨ Dilute Acid

·  Properties of acid

·  Chemical properties of Acids

¨ Reaction of Acid with Metal

¨ Reaction of Acids with Base

¨ Reaction of Acid with Metal Oxide

¨ Reaction of Acid with Metal Carbonates or Metal Hydrogen Carbonates:

·  Base

¨ Strong Base

¨ Weak Base

·  Properties of Base

·  Chemical properties of Bases

¨ Reaction of Base with some Metal

¨ Base reacts with acids

¨ Reaction of base with non metal oxide

·  pH Scale

·  Important of pH in our daily life

¨ Importance of pH in existence of living beings

¨ Importance of PH in soil

¨ Importance of pH in Digestion

¨ pH change  as the cause of tooth decay:

¨ Self-defence by animals through Chemical welfare

Acid Bases and Salts

On the bases of their chemical properties, all the components can be classified into three groups:

(1) Acid

(2) Bases

(3) Salts

Indicators:- An indicator is a dye which tells us whether the substance we are testing is an acid or a base by changing its colour. The three main indicator Litmus, Methyl orange, Phenolphthalein.

Litmus is a natural indicator obtained from the plant lichen. Methyl orange and Phenolphthalein are synthetic indicated.

An acid turn Blue Litmus to Red.

Methyl orange give Red colour in acid.

Phenopthalein is the colorless in acid solution.

Base turn Red litmus to Blue.

Methyl orange give yellow colour in base.

Phenopthalein indicator give pink in base solution.

Olfactory Indicator: Those substance whose smell or order change in acidic or basic solution are called olfactory indicator. Onion and Vanilla are olfactory indicators.

The smell of onion cannot be detected when they are treated with base. However if they are treated with acid their smell remain as usual.

Acid:

It is a substance which when dissolve in water produce H⁺ aq ions or [H₃O⁺] ions.

For example:

 (1)    

(2)    

(3)    

Organic acid: These are the acid obtained from plant and animal material and are usually weak. E.g. citric acid, Tartoric acid, lactic acid, etc.

Mineral acid: These are those acids which are obtained from the minerals of the earth and are usually strong. E.g. HCL, H₂SO₄, HNO₃.

Strong Acid: These are the acid in which completely dissociate in water to produce a large number of H⁺ ions in the solution. E.g. HCL, H₂SO₄, HNO₃.

Weak Acid: These are the acids which partially dissociate in water and thus produced a small number of H⁺ aq ions in the solution. E.g. Citric acid, latic acid etc.

Concentrated acid: it is the acid which contains minimum possible amount of water in it.

Dilute Acid: It is the acid which contain much more water that in concentrated acid.

Properties of acid:

(1) They have sour taste.

(2) They turn blue litmus to red.

(3) Acidic solution conducts electricity.

(4) Acid have corrosive nature as they produce burns on the skin.

Chemical properties of Acids:

1. Reaction of Acid with Metal: When an acid react with metal, salt corresponding to metal and H₂ gas are produced.

Acid + Metal ª Salt + Hydrogen

E.g.

 2. Reaction of Acids with Base:- When acid reacts with base then salt and water is formed. This reaction is called neutralization reaction.

Acid + Base ª Salt + Water

E.g.

 

 3. Reaction of Acid with Metal Oxide: This reaction is similar to acid and base reaction which mean that by reacting acid with metal oxide, salt and water are formed.

E.g.    2HCL + Na₂O ª 2NaCl (aq) + H₂O (L)

4. Reaction of Acid with Metal Carbonates or Metal Hydrogen Carbonates: When acid react with metal carbonates or metal hydrogen carbonates, salt water and carbon dioxide are formed.

e.g.       2HCL + Na₂ CO₃ ª 2Na Cl + H₂O + CO₂

             HCL + NaHCO₃ ª NaCl + H₂O + CO₂

Base:

These are the substance which when dissolved in water produced (OH^─) aq ions in the solution.

e.g.

 Water soluble base are known as alkalis.

Strong Base: These are the base which completed the completely dissociates in water and thus produce a large number of  (OH^─) aq ions in the solution e.g. Naoh, KOH etc.

Weak Base : These are the base which partially dissociate in water and thus produces a small number of OH^─ ions in the solution. e.g. Ca(OH)₂, Ma(OH)₂, NH₄(OH) etc.

Properties of Base:-

(1) These are bitter in taste.

(2) They turn Red Litmus to Blue.

(3) Basic solution also conducts electricity.

(4) They are soapy to touch.

Chemical properties of Bases:

1. Reaction of Base with some Metal: When a base reacts with a metal then a metal salt and hydrogen gas are formed.

Base + Metal ª Salt + Hydrogen

Note:ª Not all the metal react with base to form salt and hydrogen gas.

2. Base reacts with acids: When the base react with acid water and a salt are formed.

Base  + Acid  ª Salt + Water

e.g.

3. Reaction of base with non metal oxide:- When a base react with non metal oxide then salt and water are formed.

Base + Non-Metal Oxide ª Salt + Water

 

pH Scale :	[Power of Hydrogen]
	[Petenz de Hydrogen]

The pH of any solution is inversely proportional to the concentrated of H⁺ (aq) in that solution.

Higher the concentrated of H⁺ ions lower will be the pH an lower the concentrated of H⁺ ions higher will be the pH.

The strength of acid or base is measured by a scale of numbers from 0-14 called the pH Scale.

       pH = ― log [H⁺]

Points to Remember:- In pure water the concentrated of H⁺ ions and OH ^─ ions are equal. Hence pure water is neither acidic nor basis, it is neutral.

(a) Acids have pH less than 7.

(b) Bases have pH more than 7.

Important of pH in our daily life:

(a) Importance of pH in existence of living beings:- Our Body works within the pH range of 7.0 to 7.8. Living organism survive only in the narrow range of pH. When pH of rain water is less than 5.6, it is called as a acid rain. When acid rain flows in to the soil or river, it lower the pH and the survival of plants and aquatic life in the river become difficult.

(b) Importance of PH in soil: the soil as whose pH is between 6•5 to 7•3 is good for plants growth.

If less than 6•5 , it is acidic and more than 7•3, it becomes alkaline soil.

(c) Importance of pH in Digestion: HCL secreate in the stomach. The pH change between 1 to 3. At this low value of pH the enzymes named pepsin becomes active. Sometimes due to more secretion of HCL, there is pain or irritation in the stomach. i.e. acidity. Basic substance are taken for remedy of the acidity such as Mg(OH)₂ and NaHCO₃ . These are also known as antacids.

(d) pH change  as the cause of tooth decay: Tooth decay start when the pH of the mouth is lower than 5•5 . tooth are made of calcium phosphate and it is the hardest substance in the body.

Bacteria present in the mouth produced acid by degradation of sugar and food particles remaining in the mouth after eating. Toothpaste are basic in nature . So, it neutralize the excess acid by prevent tooth decay.

(e) Self-defence by animals through Chemical welfare:- Many plants and animals protect themselves from enemies by injecting painfull and irritating acid into the enemy bodies. E.g. Red ant bites, we feel irritation as this is the entry of formic acid in our body. To get the relief from the effect of bite; basic substance like baking soda applied around the place of bite. It neutralize acidic poison and gives relief.

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