Materials Required

Dilute hydrochloric acid, dilute sodium hydroxide solution, phenolphthalein indicator, test tubes, dropper, test-tube stand.

Procedure

Take about 5 mL of dilute hydrochloric acid in a test tube.
Add 1-2 drops of phenolphthalein indicator to the solution and note down if any change in colour.
Take about 10 mL of dilute sodium hydroxide solution in another test tube.
Take out sodium hydroxide solution with the help of a dropper and start adding this solution dropwise into the test tube containing hydrochloric acid till a change in colour is observed
What colour do you get?
With the help of another dropper, take out hydrochloric acid and start adding it dropwise into the coloured solution obtained above.
Note your observation

Click the Cap of Hydrochloric acid to open the glass bottle.
Drag the bottle into the measuring Cylinder.
Drop the bottle to pour 5ml of solution into the measuring cylinder.
Drag and drop the measuring cylinder containing 5ml Hydrochloric solution to the Test-tube A.
Drag the dropper to add 1 to 2 drops of phenolphthalein into the test-tube A.
Click the cap of Sodium Hydroxide to open the glass bottle.
Drag the bottle into the measuring cylinder.
Drop the bottle to pour 10ml of solution into the measuring cylinder.
Drag and drop the measuring cylinder into the test tube B and pour 10ml solution.
Drag and drop the dropper to test tube B.
Drag the Dropper to test tube A containing the mixture of Hydrochloric acid and phenolphthalein.
Drop the dropper to add the solution dropwise to test tube A.
Show a colour change solution to Pink.
Click the Cap of Hydrochloric acid to open the glass bottle.
Drag the bottle into the measuring Cylinder.
Drop the bottle to pour 5ml of solution into the measuring cylinder.
Drag and drop the measuring cylinder containing 5ml Hydrochloric solution to the Test-tube A.

Colour of the hydrochloric acid solution does not change on addition of phenolphthalein indicator.
On adding nearly 5 mL sodium hydroxide solution to the mixture of hydrochloric acid and phenolphthalein solution, the colour of the mixture changes to pink.
On addition of hydrochloric acid solution to the pink solution, the colour starts fading gradually and finally the solution becomes colourless.

Phenolphthalein indicator remains colourless in the acidic solution while its colour changes to pink in basic solution.
It is found that on adding a base in an acid, a stage reaches when effect of acid is neutralised by base and vice-versa as indicated by colour changes of indicator.

Be careful while handing the acid carefully.