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1. ACIDS,BASES
AND SALTS
CLASS-7 CHAPTER 5
CHEMISTRY

2. ACIDS
A substance with particular chemical
properties turning litmus red, neutralizing
alkalis and dissolving some metals ;
typically a corrosive or sour –tasting liquid
is known as acid.The word acid comes from
the Latin word acere which means sour.
Acids can classified into two:
1. Weak acid
2. Strong acid

3. 1. WEAK ACID
• Mild in nature.
• Do not cause burns on skin.
• Example: Acetic acid, Oxalic acid, Lactic acid
2. STRONG ACID
• Corrosive in nature.
• Cause burns on skin.
• Example: Sulphuric acid, Hydrochloric acid

4. Based on source, acid can also be grouped into
two:
ACID
ACIDS
Organic acid
Obtained from organic
materials such as plants
and animals
Ex: citric acid , acetic acid
Inorganic acid
Obtained from minerals,
also called inorganic acid.
Ex: sulphuric acid , nitric
acid

5. PROPERTIES OF ACIDS
 Sour to taste.
 Soluble in water.
 Conduct electricity.
 Corrosive in nature.
 Can be stored in plastic/ glass
container

6. SOME USES OF ACIDS
1. CITRIC ACID
• It is used as a preservative for food
• It is used as a flavouring agent.
2.ASCORBIC ACID
• It is used in the treatment of bone marrow and
scurvy diseases.
3. ACETIC ACID
• It is added to pickles to make them sour.
• It helps to remove stains on woodwork such as
furniture and carpets.

7. 4. SULPHURIC ACID
• It is used in car batteries.
5. PHOSPHRIC ACID
• It is used in fertilizers.
• It is also used in detergent industries.
6. NITRIC ACID
• It is used by goldsmith for cleaning gold and
silver ornaments.
7. HYDROCHLORIC ACID

8. BASES
The substances which are bitter to taste
and slippery to touch are known as Bases.
Bases can be classified into two based on
their strength:
1. STRONG BASE
2. WEAK BASE

9. 1. STRONG BASE
• These bases are strong and can be
corrosive in nature.
• Example: sodium hydroxide, potassium
hydroxide.
2. WEAK BASES
• These bases are mild and are not
corrosive in nature.
•Example: ammonia , methylamine and
magnesium hydroxide.

10. PROPERTIES OF BASES
 Slippery to touch.
 Bitter to taste.
 Conduct electricity.
 Few bases are water soluble.
 Few base are not water
soluble.

11. SOME USES OF BASES
1. SODIUM HYDROXIDE
• It is used in the manufacturing of medicines.
• It is used in the manufacturing of paper ,
rayon and textiles.
• It is also used in the manufacturing of soaps
and detergent.
2. POTASSIUM HYDROXIDE
• It is used in the production of disinfectants.
• It is used in the manufacturing of liquid soap ,

12. 3. MAGNESIUM HYDROXIDE
• It is used in the preparation of antacids to
neutralize acidity in our stomach.
4. CALCIUM HYDROXIDE
• It is used in the manufacturing of bleaching
powder.
• It is used in the manufacturing of cements.
• It is used in the manufacturing of agricultural
pesticides.
5. AMMONIUM HYDROXIDE

13. INDICATORS
Special type of substances which are
used to test whether a substances is
acidic or basic are known as indicators.
Indicators can be divided into groups
based on their origin.
1.NATURAL INDICATORS
2. SYNTHETIC INDICATORS

14. INDICATORS
Natural
indicators
The indicators that
are obtained from
plants are known as
natural indicators.
Synthetic
indicators
The indicators which
are manmade are
known as synthetic
indicator.

15. NEUTRALIZATION
REACTION
The reaction between an acid and a base to form
salt and water is called neutralization reaction.
Example : sodium hydroxide+ hydrochloric acid
= sodium chloride ( salt ) +water