Question

Equal volumes of hydrochloric acid and sodium hydroxide solutions of the same concentration are mixed and the pH of the resulting solution is checked with a pH paper. What would be the colour obtained?

• A. Red
• B. Yellow
• C. Yellowish green
• D. Blue

Answer 1

The correct option is C

Yellowish green

Explanation

pH: is a measure of how acidic/basic the solution is. The range goes from 0 - to 14, with 7 being neutral. A pH of less than 7 indicates acidity, whereas a pH of greater than 7 indicates a base.

The explanation for the Correct answer

• Here neutralization takes place between $\mathrm{HCl}$ and $\mathrm{NaOH}$ solution hence pH will remain neutral which will be in the yellowish-green zone in pH paper.
• $\underset{\mathrm{hydrochloric}\mathrm{acid}}{\mathrm{HCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{sodium}\mathrm{hydroxide}}{\mathrm{NaOH}\left(\mathrm{aq}\right)}\to \underset{\mathrm{sodium}\mathrm{chloride}}{\mathrm{NaCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)}$

Therefore equal volumes of hydrochloric acid and sodium hydroxide solutions of the same concentration are mixed and the pH of the resulting solution is checked with the colour obtained is Yellowish green.