Question

Acetic acid is a weak acid. If equal volumes of equal molar solutions (with a strong base) are mixed, the $pH$ of a solution will be:

• A. more than 7
• B. less than 7
• C. equal to 7
• D. can't say

Answer 1

The correct option is A more than 7

The reaction is:

$NaOH\left(aq\right)+$ $H{C}_2{H}_3{O}_2$$\left(aq\right)\to$ $H_{2}O\left(l\right)$ + $Na{C}_2{H}_3{O}_2\left(aq\right)$

The acetate ion produced ($C_2{H}_3{O}_2^{-}$). This will react slightly with water (i.e. act as a weak base by accepting a $H^{+}$ from $H_{2}O$) to produce a small amount of $O{H}^{-}$.

$C_2{H}_3{O}_2^{-}\left(aq\right)$ + $H_{2}O\left(l\right)\to$ $H{C}_2{H}_3{O}_2\left(aq\right)$ + $O{H}^{-}\left(aq\right)$

This small amount of $O{H}^{-}$ produced makes the solution slightly alkaline.

Therefore the pH value overcomes 7. Hence, the correct option is A.