Question

A litmus paper was dropped into 2ml dilute HCl. Then 2ml concentrated NaOH was added to it and stirred.  

Write down the changes that will be seen in each instance and explain the reason behind it.

(d) A litmus paper was dropped into 2ml dilute HCl. Then 2ml concentrated NaOH was added to it and stirred.

Answer 1

When litmus paper is dipped into 2 mL of dilute HCl solution , then blue litmus paper is turned into red colour and there is no effect on red litmus paper. Again, if the 2 mL of concentrated NaOH solution added in the same solution, same litmus paper is dipped into, then red litmus paper turns into blue colour but there is no effect on blue litmus paper. This is due to the respective properties of blue and red litmus paper with acid and base.