Question

notes for acid base salts class7
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Answer 1

Explanation:

Acids and Bases

Acids

• Acids are substances that taste sour and are corrosive in nature.
• It turns blue litmus paper to red.
• These substances are chemically acidic in nature.E.g.:-orange juice, curd, vinegar, hydrochloric acid etc.

Bases

• Bases are substances that, in aqueous solution, are slippery to the touch and bitter in taste.
• It turns red litmus paper to blue.
• These substances are chemically basic in nature. Eg:- soap, ammonium hydroxide, calcium hydroxide, etc.

Neutralisation Reaction

• When an acid and base react with each other to form a salt, water and heat then such reaction is known as neutralisation reaction.
• In this reaction, the acidic and basic nature of the acid and base respectively are destroyed.
• The reaction between hydrochloric acid and sodium hydroxide is a classic neutralisation reaction where sodium chloride is formed.

HCl+NaOH→NaCl(salt)+H²O

Salts

• Salt is the product formed from the neutralisation reaction of acids and bases.
• In the reaction between hydrochloric acid and sodium hydroxide the salt formed is sodium chloride.

HCl+NaOH→NaCl+H2O

• Salt can be acidic, basic or neutral in nature.

Answer 2

Answer:

Acids

An acid is a sour-tasting substance which posseses certain chemical properties . Substances which contain acids are said to be acidic in nature.

Bases

The substances , which are bitter to taste and soapy to touch, are known as bases. Substances which contain bases are said to be basic in nature.

Salts

We known that phenolphthalein is an indicator which shows pink colour in basic solutions but does not show any colour in acidic solutions . When the acid was added to the test tube in sufficent amount , the pink colour of phenophthalein disappeared. This suggests that some reaction occured between the acid and the base, in which they neutralised each others effects. Such reactions are known as neutralisation reactions. The product formed in this reaction is known as salt.