A buffer is made from 0.10 M NaH₂PO₄ and 0.10 M Na₂HPO₄

CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases

Problem

A buffer is made from 0.10 M NaH₂PO₄ and 0.10 M Na₂HPO₄. When a small amount of NaOH(aq) is added, which balanced net ionic equation occurs? (a)

\mathrm{H_2PO_4^- \rightleftharpoons HPO_4^{2-} + H^+}

(b)

2\,\mathrm{OH^- + H_2PO_4^- \rightarrow PO_4^{3-} + 2\,H_2O}

(c)

\mathrm{OH^- + H_2PO_4^- \rightarrow HPO_4^{2-} + H_2O}

(d)

\mathrm{OH^- + HPO_4^{2-} \rightarrow PO_4^{3-} + H_2O}