It covers the topics-Acids,Bases and their types ,Indicators--natural and Artificial

1. LEARNING OBJECTIVES
 INTRODUCTION
 ACIDS
 BASES
 INDICATORS
 NATURAL INDICATORS
(1) LITMUS – NATURAL DYE
(2) CHINA ROSE
(3) TURMERIC

2. INTRODUCTION
 In our daily life , we use a large number of edible substances
such as lemon , baking soda , tamarind ,common salt and
vinegar etc.
 Acids , Bases , and Salts are the three important groups of
chemical substances that are used by us in different ways .

3. ACIDS
 Curd , orange juice , and vinegar taste sour due to acids
present in them . The chemical nature of such substances is
acidic .
 The acids in these substances is natural acids.
 Acid has been derived from a latin word ‘acidus’ which
means sour .
 Acids can be –1.Natural ---found in plants and animals.They
are weak acids.
 E.g Lactic acid, Acetic acid
 2.Artificial---made in labs. They are strong
acids.
 E.g HCl, Sulfuric Acid, Nitric acid.

4. BASES
 For example baking soda it is not sour in taste so it is not
acidic . But it is bitter is taste and feel soapy on touching .
So these are bases . The nature of these substances is basic .
These can also be called alkalis.
 Examples are Potassium Hydroxide , Ammonium Hydroxide ,
Sodium Hydroxide , Magnesium Hydroxide .

5. INDICATORS
 Special type of substances are used to check whether the
substances are acidic or basic in nature . These special type of
substances are called Indicators .
 The indicators change their color when added to any of acid or
base .
 They can be natural or artificial .
 Examples of natural are Turmeric , China Rose and Litmus .

6. Artificial indicators
 1.Phenolphthalein:.
 2.Methyl orange:

7. LITMUS – A NATURAL DYE
 Litmus is extracted from lichens . It has mauve
(purple) color in distilled water .
 Now a days available in paper strips form ---Red
litmus paper and Blue litmus paper.
 When litmus is added to acids it turns red and
when added to bases it turns blue .
 But if substance do not change it color to red or
blue litmus are called neutral solutions.

9. TURMERIC

10. CHINA ROSE

11.  Soaking China Rose petals in hot water creates
a solution that can be used as acid – base
indicator .
 Acids turn china rose to red color or pink color.
 Bases turn china rose to yellow and greenish
color .

12. ACIDS AND BASES

13. RECAP OF DEFINITIONS
Any substance that is sour in taste are
acidic in nature . Example - Lemon
Any that is bitter in taste and feel soapy
are basic in nature . Example – Sodium
Hydroxide .

14. SUMMARY
 Today we learnt about acids and bases and their
examples
 Then we studied about how to check whether the
substance is acidic or basic in nature that is
indicators .
 We learnt many examples of indicators by
examples .