pKa Calculator
Calculate pKa from Ka, determine acid strength, pH of weak acid solutions, and percent dissociation.
Calculator Settings
Calculate:
Common Acids:
pKa Value
4.74
Moderate Acid
Ka
1.800e-5
Kb (conjugate base)
5.556e-10
pKb
9.26
pH at 0.1 M
2.87
Percent Dissociation
1.34%
[H+] = 1.342e-3 M
Formula:
pKa = -log(Ka)
pKa + pKb = 14 (at 25C)
Understanding pKa
pKa is the negative logarithm of the acid dissociation constant (Ka). It indicates the strength of an acid - the lower the pKa, the stronger the acid. At the pKa value, exactly half of the acid molecules are dissociated. This value is crucial in buffer preparation, drug design, and understanding acid-base equilibria.
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
Formula Source: Chemistry: The Central Science
by Brown, LeMay, Bursten