Question

A solution of $N{a}_{3}C{O}_3$ is alkaline? Explain.

Answer 1

When sodium carbonate dissolves in water it dissociates into two sodium ($N{a}^{+}$) ions and a carbonate ($C{O}_3^{–2}$) ion;-

$N{a}_{2}C{O}_3\left(s\right)\to 2N{a}^{+}\left(aq\right)+C{O}_3^{–2}\left(aq\right)$

The carbonate ion is able to remove protons ($H^{+}$) from water to form bicarbonate ions and hydroxide ions. Hence it is the conjugate base of the bicarbonate ion;

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

The overall increase in $O{H}^{-}$ ions due to these reactions results in an increase in the pH of the solution, and cause it to become alkaline.