# Henderson-Hasselbalch equation

(redirected from Hasselhoff equation)

## equation

[e-kwa´zhun]
an expression of equality between two parts.
Henderson-Hasselbalch equation a formula for calculating the pH of a buffer solution such as blood plasma, pH = pKa + log [BA/HA]; [HA] is the concentration of a free weak acid; [BA] the concentration of the ionized form of this acid; pKa the acid dissociation constant, a measure of the ionization equilibrium of the acid.

## Hen·der·son-Has·sel·balch e·qua·tion

(hen'dĕr-sŏn hahs'ĕl-bawlk),
a formula relating the pH value of a solution to the pKa value of the acid in the solution and the ratio of the acid and the conjugate base concentrations: pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the conjugate base and [HA] is the concentration of the protonated acid. For the bicarbonate buffer system in blood, pH = pK' + log([HCO3-]/[CO2]). The value of pK' for blood plasma is 6.10 and includes the first dissociation constant of H2CO3, the relation between [H2CO3] and [CO2], and other corrections. The partial pressure of CO2 multiplied by its solubility in plasma at 38°C (0.0301 mM/mm Hg) is commonly substituted for [CO2]; for example, when the plasma bicarbonate concentration is 24 mEq/L and the PCO2 is 40 mm Hg, the pH value is 6.10 + log(24/0.0301 × 40) = 7.40.
[Lawrence J. Henderson, Karl Hasselbalch]

## Henderson-Hasselbalch equation

Etymology: Lawrence J. Henderson, American chemist, 1878-1942; Karl A. Hasselbalch, Danish biochemist, 1874-1962
the relationship among pH, the pKa of a buffer system, and the ratio of the concentrations of the weak acid and its conjugate base.

## Hen·der·son-Has·sel·balch e·qua·tion

(hen'dĕr-sŏn hahs'ĕl-bawlk ĕ-kwā'zhŭn)
A formula relating the pH value of a solution to the pKa value of the acid in the solution and the ratio of the acid and the conjugate base concentrations: pH = pKa + log ([A-]/[HA]) where [A-] is the concentration of the conjugate base and [HA] is the concentration of the protonated acid.
[Lawrence J. Henderson, Karl Hasselbalch]

## Hasselbalch,

Karl, Danish biochemist and physician, 1874-1962.
Henderson-Hasselbalch equation - see under Henderson

## Henderson,

Lawrence J., U.S. biochemist, 1879-1942.
Henderson-Hasselbalch equation - a formula relating the pH value of a solution to the value of the acid in the solution and the ratio of the acid and the conjugate base concentrations.

## Henderson-Hasselbalch equation

an equation by which the pH of a buffer solution, blood plasma being such a one, can be determined:$$\hbox{pH=pK\'^\prime}+\log{[\hbox{BA}]\over[\hbox{HA}]}$$
where pK′ is the negative log of the dissociation constant of a weak acid in a buffer solution, [HA] is the concentration in the buffer solution of the weak acid and [BA] is the concentration of a salt of that acid.
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