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SAI INTERNATIONAL SCHOOL
CLASS-VII
Subject-Chemistry
Topic- ACIDS, BASES & SALTS

CLASS ROOM ACTIVITY

EXPERIMENT: To understand the neutralization reaction of acid and base.

Materials Required: - A conical flask containing dilute hydrochloric acid. Test
tube, One dropper, Hydrochloric acid, Sodium hydroxide and Phenolphthalein
as indicator.

Observation: i) When 2drops of phenolphthalein is added to the test tube containing
10 drops of hydrochloric acid, no change of colour took place.

ii) Again on adding few drops of sodium hydroxide solution to the above mixture,

colour of the solution turned in to pink.

Inference:

i) Phenolphthalein is used as an indicator which indicates presence of basic
solution by changing colourless solution into pink.
ii) When acid react with base it nullified both acidic and basic effect and
produce salt and water which is identified by changing colour from pink to
colourless.

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