Table 2.

Capillary model buffer equilibrium coefficients

		KEQ	pK
Plasma buffers
[H+]·[${\text{HCO}}_3^{-}$]	[H2CO3]	2.69 × 10−4	3.57
[H+]·[${\text{HPO}}_4^{2-}$]	[${\text{H}}_2{\text{PO}}_4^{-}$]	1.58 × 10−7	6.80
[H+]·[NH3]	[${\text{NH}}_4^{+}$]	7.08 × 10−10	9.15
[H+]·[${\text{HCO}}_2^{-}$]	[${\text{HCO}}_2^{-}$]	1.74 × 10−4	3.76
Hemoglobin buffers
[H+]·[HbO2NH2]	[${\text{HbO}}_2{\text{NH}}_3^{+}$]	1.79 × 10−8	7.75
[H+]·[HbNH2]	[${\text{HbNH}}_3^{+}$]	3.98 × 10−8	7.40
[H+]·[HbO2X−]	[HbO2XH]	2.14 × 10−7	6.70
[H+]·[HbX−]	[HbXH]	1.00 × 10−7	7.00
[H+]·[HbO2Y−]	[HbO2YH]	1.45 × 10−8	7.84
[H+]·[HbY−]	[HbYH]	8.13 × 10−9	8.09
[H+]·[${\text{HbO}}_2{\text{NHCO}}_2^{-}$]	[CO2]·[HbO2NH2]	1.13 × 10−5
[H+]·[${\text{HbNHCO}}_2^{-}$]	[CO2]·[HbNH2]	2.15 × 10−5

Equilibrium coefficients $K_{{}_{EQ}}=\frac{\left[{\text{H}}^{+}\right]\cdot \left[{\text{B}}^{-}\right]}{\left[HB\right]}$ or $K_{{}_{EQ}}=\frac{\left[{\text{H}}^{+}\right]\cdot \left[{\text{BCO}}_2^{-}\right]}{\left[HB\right]\cdot \left[{\text{CO}}_2\right]}$.