A buffer is prepared by dissolving 0.200 mol of and 0.150 mol of in water to make…

CHEMISTRY · Subjective · A Level · Chemistry · Acids and bases · Acids and bases

Problem

A buffer is prepared by dissolving 0.200 mol of

\mathrm{Na_2HPO_4}

and 0.150 mol of

\mathrm{NaH_2PO_4}

in water to make 1.00 L of solution. For phosphoric acid,

pK_{a1}=2.15

pK_{a2}=7.21

, and

pK_{a3}=12.38

. Calculate the pH of the buffer, identifying which

pK_a

value is appropriate for your calculation.