Chapter 14: Q2E (page 826)
Question: Write equations that show \({H_2}PO_4^ - \) acting both as an acid and as a base.
Short Answer
When \({H_2}PO_4^ - \) reacts with \({H_2}O\), it gives proton to water. As a result, it acts as an acid. The equation regarding this is as follows
\({H_2}PO_4^ - + {H_2}O \to HPO_4^{2 - } + {H_3}{O^ + }\)
When \({H_2}PO_4^ - \) reacts with \(HCl\), it takes proton from \(HCl\). As a result, it acts as a base.
The equation regarding this is as follows
\({H_2}PO_4^ - + HCl \to {H_3}P{O_4} + C{l^ - }\)