Which an activity to find the change of colour

CBSE Class 10 CBSE Class 10 Science
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Which an activity to find the change of colour in the reaction of an acid with a base (Neutralization) reaction.

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Aim : To test the change of colour in the reaction of an acid with a base.
Required Materials :

  1. 2 ml of dilute NaOH (Sodium Hydroxide) solution.
  2. Phenolphthalein indicator solution.
  3. Dilute HCZ (Hydrochloric) solution.
    Procedure :
  4. Take about 2ml of dilute NaOH solution in a test tube.
  5. Add two drops of phenolphthalein indicator solution.
    Observation (i) :
  6. It turns to red or pink colour.
  7. It shows that NaOH is a base.
    Experiment (1) : Add dilute HCZ solution to the above solution drop by drop. Observation (ii) : Pink colour disappears due to the reaction of NaOH (base) with HCZ (acid).
    Experiment (2) : Now add one or two drops of NaOH to the above mixture. Observation (iii) : Pink colour reappears on adding NaOH.

    Result: This reaction is called a neutralization reaction.