(Solved): Phosphoric acid is a triprotic acid with the pKa values pKa1=2.148,pKa2=7.198, and pKa3 ...

Phosphoric acid is a triprotic acid with the $\mathrm{p}{K}_{\mathrm{a}}$ values $\mathrm{p}{K}_{\mathrm{a}1}=2.148,\mathrm{p}{K}_{\mathrm{a}2}=7.198$, and $\mathrm{p}{K}_{\mathrm{a}3}=12.375$. You wish to prepare $1.000\mathrm{L}$ of a $0.0200\mathrm{M}$ phosphate buffer at $\mathrm{pH}7.580$. To do this, you choose to mix the two salt forms involved in the second ionization, ${\mathrm{NaH}}_2{\mathrm{PO}}_4$ and ${\mathrm{Na}}_2{\mathrm{HPO}}_4$, in a $1.000\mathrm{L}$ volumetric flask and add water to the mark. What mass of each salt will you add to the mixture? mass ${\mathrm{NaH}}_2{\mathrm{PO}}_4=$ mass ${\mathrm{Na}}_2{\mathrm{HPO}}_4=$ g What other combination of phosphoric acid and its salts could be mixed to prepare this buffer? $\begin{array}{l}{\mathrm{H}}_3{\mathrm{PO}}_4\text{ and }{\mathrm{Na}}_2{\mathrm{HPO}}_4\\ {\mathrm{H}}_3{\mathrm{PO}}_4\text{ and }{\mathrm{NaH}}_2{\mathrm{PO}}_4\\ {\mathrm{H}}_3{\mathrm{PO}}_4\text{ and }{\mathrm{Na}}_3{\mathrm{PO}}_4\\ {\mathrm{NaH}}_2{\mathrm{PO}}_4\text{ and }{\mathrm{Na}}_3{\mathrm{PO}}_4\\ {\mathrm{Na}}_2{\mathrm{HPO}}_4\text{ and }{\mathrm{Na}}_3{\mathrm{PO}}_4\end{array}$