Question

P and Q are aqueous solutions of sodium chloride and sodium hydroxide, respectively. Which of these will turn:

1. blue litmus red?
2. red litmus blue?

Answer 1

1. Neither solution will turn blue litmus red. Solution P is sodium chloride, formed from a strong acid, hydrochloric acid (HCl), and a strong base, sodium hydroxide (NaOH). When sodium chloride is dissolved in water, it dissociates to give equal amounts of hydroxide and hydrogen ions, making its aqueous solution neutral. Therefore, a sodium chloride solution will have no effect on red or blue litmus paper.

2. Sodium hydroxide solution (Q) will turn red litmus paper blue because it is basic.