Question

When few drops of phenolphthalein are added to a dilute solution hydroxide a pink colour is produced. What will be the colour of the final mixture when excess of $HCl$ is added to it?

(justify your answer)

Answer 1

Acid + Base $\to$ Salt + Water

Phenolphthalein, being a chemical indicator, giver pink colour in basic solutions and gets colourless in acidic solutions. Upon the addition of $HCl$ to the $NaOH$ solution leads to the reaction of neutralisation,

$NaOH+HCl\to NaCl+H_{2}O$

But upon addition of excess of $HCl$ makes the solution acidic hence, the solution gets colourless at the end of the experiment.