Question

The net ionic equation for the aqueous neutralization reaction between acetic acid and sodium hydroxide is different from that for the reaction between hydrochloric acid and sodium hydroxide. Explain by writing balanced net ionic equations.

Short answer

Answer

A weak acid does not dissociate completely in an aqueous medium. But a strong acid dissociates completely. So when the reaction occurs between weak acid and a strong base complete neutralization does not occur. But when a reaction occurs between a strong acid and a strong base complete neutralization occurs.

Step-by-step solution

Write the net ionic equation

The net ionic equation of reaction between acetic acid and sodium hydroxide is:

${\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right)+{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)\to {\mathrm{CH}}_3{\mathrm{COO}}^{-}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(1\right)$

The net ionic equation of reaction between hydrochloric acid and sodium hydroxide is:

${\mathrm{H}}^{+}\left(\mathrm{aq}\right)+{\mathrm{OH}}^{-}\left(\mathrm{aq}\right){\mathrm{H}}_2\mathrm{O}\left(\mathrm{I}\right)$

Determine the difference between the neutralization reaction of acetic acid and sodium hydroxide, and hydrochloric acid and sodium hydroxide

When the reaction occurs between weak acid and a strong base do not generally result in a neutral solution.

When the reaction between weak acid (acetic acid) and a strong base (sodium hydroxide) occurs the molecules of weak acid do not dissociate completely in the water while the strong base gets completely dissociated.

The sodium ion is the spectator ion. The strong hydroxide ion forces the weak acetic acid to become ionized. The hydrogen ion from weak acid combines with hydroxide ion and forms water, leaving acetate ion as the other product.

It makes the solution slightly basic.

When a reaction occurs between a strong acid and a strong base, it results in a neutral solution.

In the case of HCl and NaOH, one is a strong acid and the other is a strong base hence in an aqueous medium both are dissociated completely and form NaCl as a product, here sodium and chloride are present on both sides of the reaction, thus both are spectator ions in the reaction hence in the net ionic equation hydrogen ion combine with the hydroxide ion to produce water and makes the solution neutral with pH value 7.