Table 1.

Oxoacid and oxoanion volumes

Oxoacid/Oxoanion	Gas Phase VM, cm3/mol	Implicit Aqueous Solvent VM, cm3/mol
$\mathrm{H}\mathrm{C}{\mathrm{O}}_{\mathrm{3}}^{\mathrm{-}}$	41.9	39.1
H3BO3	43.4	43.6
${\mathrm{H}}_{\mathrm{4}}\mathrm{B}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{-}}$	52.5	55.8
H4SiO4	63.2	56.5
H4GeO4	61.3	57.8
$\mathrm{H}\mathrm{P}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}\mathrm{-}}$	62.0	59.2
$\mathrm{H}\mathrm{A}\mathrm{s}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}\mathrm{-}}$	65.0	63.1

PBE0/6–31++g(d,p) calculated solvent accessible surface molar volumes (V_M) for various main group oxoacids and oxoanions at physiological pH, showing the similarities between H₄SiO₄, H₄GeO₄ (two oxoacids that are effluxed by Slc34a2), $\mathrm{H}\mathrm{P}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}\mathrm{-}}$, and $\mathrm{H}\mathrm{A}\mathrm{s}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}\mathrm{-}}$ (oxoanions that are influxed by Slc34a2).