Acids, Bases and Salts21Activity 2.6Activity 2.6Activity 2.6Activity 2.6Activity 2.6square6Take about 2 mL of dilute NaOH solution in a test tube and addtwo drops of phenolphthalein solution.square6What is the colour of the solution?square6Add dilute HCl solution to the above solution drop by drop.square6Is there any colour change for the reaction mixture?square6Why did the colour of phenolphthalein change after the additionof an acid?square6Now add a few drops of NaOH to the above mixture.square6Does the pink colour of phenolphthalein reappear?
Why do you think this has happened?
In the above Activity, we have observed that the effect of a base isnullified by an acid and vice-versa. The reaction taking place is written as –NaOH(aq) + HCl(aq) →NaCl(aq) + H2O(l)The reaction between an acid and a base to give a salt and water isknown as a neutralisation reaction. In general, a neutralisation reactioncan be written as –Base + Acid →Salt + Water