Why do aqueous solutions of phenol give acidic solutions?

Jul 31, 2017

You've got phenol, ${C}_{6} {H}_{5} O H$.....?

Explanation:

Because the $\text{phenoxide anion}$ is stabilized somewhat by resonance, and delocalization of charge density, $\text{phenol}$, and its derivatives are mildly acidic......

${C}_{6} {H}_{5} O H \left(a q\right) + {H}_{2} O \left(l\right) \rightarrow {C}_{6} {H}_{5} {O}^{-} + {H}_{3} {O}^{+}$

or since you specified an $\text{Arrhenius acid} \ldots \ldots \ldots$

${C}_{6} {H}_{5} O H \left(a q\right) \stackrel{{H}_{2} O}{\rightarrow} {C}_{6} {H}_{5} {O}^{-} + {H}^{+}$

$p {K}_{a} = 8.00$

Substitution of the ring by nitro groups that cause the charge density of the anion to DECREASE, causes the acidity to increase. $\text{1,3,5-trinitrophenol}$, $1 , 3 , 5 - {\left({O}_{2} N\right)}_{3} {C}_{6} {H}_{2} O H$ is otherwise known as $\text{picric acid}$, whose $p {K}_{a} = 0.38$, very strong for a carbon acid.