Question

Two test tubes containing water are labelled A and B. A few drops of hydrochloric acid and acetic acid are added to test tube A and test tube B respectively. Which of the following statements are true regarding the number of $H^{+}$ ions in the test tubes?

• A. Test tube A has more number of $H^{+}$ ions than test tube B.
• B. Test tube B has more number of $H^{+}$ ions than test tube A.
• C. Both the test tubes have equal number of $H^{+}$ ions.

Answer 1

The correct option is A Test tube A has more number of $H^{+}$ ions than test tube B.

Acetic acid, $C{H}_{3}COOH$ is a weak acid and gets partially ionised in water that is not all molecules of acetic acid ionise to form $C{H}_{3}CO{O}^{-}$ and $H^{+}$ ions.

The chemical reaction is given as:
$C{H}_{3}COOH\left(aq\right)\leftrightharpoons H^{+}\left(aq\right)+C{H}^{3}CO{O}^{-}\left(aq\right)$

On the other hand, hydrogen chloride ($HCl$) is a strong acid. It ionises completely in water to form $H^{+}$ and $C{l}^{-}$ ions.

The chemical reaction is given as:
$HCl\left(aq\right)\to H^{+}\left(aq\right)+C{l}^{-}\left(aq\right)$

Therefore, test tube A which has hydrochloric acid will have more number of $H^{+}$ ions in aqueous solution than test tube B which has acetic acid.