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SAI International School
Class-VII
Subject-Chemistry
Topic-Acids, Bases and Salts
Sub-topic- Differences between acids and bases, Indicators
LESSON NOTES
DIFFERENCES BETWEEN ACIDS AND BASES:
Acids and bases are substances which have a number of differences
between them. The differences between them are listed below:
Property Acids Bases
Taste Sour Bitter
Feel Corrosive in nature Soapy to touch
Reaction to They turn blue litmus paper They turn red litmus paper
litmus paper red blue
pH value pH value is less than 7 pH value is more than 7
Reactions React with bases to form salt React with acids to form
and water salt and water
INDICATORS:
An indicator is a substance that changes colour in the presence of an
acid or a base. It is used to identify whether a substance is acidic or
basic in nature.
TYPES OF INDICATORS:
Natural indicators:
Indicators which are obtained from nature like turmeric, red cabbage,
China rose and litmus solutions.
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