12.3: Acid Dissociation Constants
- Page ID
- 538337
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)| Name | Formula | K a1 | pKa1 | K a2 | pKa2 | K a3 | pKa3 | K a4 | pKa4 |
|---|---|---|---|---|---|---|---|---|---|
| Acetic acid | \(\ce{CH3CO2H}\) | 1.75 × 10−5 | 4.756 | - | - | - | - | - | - |
| Arsenic acid | \(\ce{H3AsO4}\) | 5.5 × 10−3 | 2.26 | 1.7 × 10−7 | 6.76 | 5.1 × 10−12 | 11.29 | - | - |
| Benzoic acid | \(\ce{C6H5CO2H}\) | 6.25 × 10−5 | 4.204 | - | - | - | - | - | - |
| Boric acid | \(\ce{H3BO3}\) | 5.4 × 10−10* | 9.27* | >1 × 10−14* | >14* | - | - | - | - |
| Bromoacetic acid | \(\ce{CH2BrCO2H}\) | 1.3 × 10−3 | 2.90 | - | - | - | - | - | - |
| Carbonic acid | \(\ce{H2CO3}\) | 4.5 × 10−7 | 6.35 | 4.7 × 10−11 | 10.33 | - | - | - | - |
| Chloroacetic acid | \(\ce{CH2ClCO2H}\) | 1.3 × 10−3 | 2.87 | - | - | - | - | - | - |
| Chlorous acid | \(\ce{HClO2}\) | 1.1 × 10−2 | 1.94 | - | - | - | - | - | - |
| Chromic acid | \(\ce{H2CrO4}\) | 1.8 × 10−1 | 0.74 | 3.2 × 10−7 | 6.49 | - | - | - | - |
| Citric acid | \(\ce{C6H8O7}\) | 7.4 × 10−4 | 3.13 | 1.7 × 10−5 | 4.76 | 4.0 × 10−7 | 6.40 | - | - |
| Cyanic acid | \(\ce{HCNO}\) | 3.5 × 10−4 | 3.46 | - | - | - | - | - | - |
| Dichloroacetic acid | \(\ce{CHCl2CO2H}\) | 4.5 × 10−2 | 1.35 | - | - | - | - | - | - |
| Fluoroacetic acid | \(\ce{CH2FCO2H}\) | 2.6 × 10−3 | 2.59 | - | - | - | - | - | - |
| Formic acid | \(\ce{CH2O2}\) | 1.8 × 10−4 | 3.75 | - | - | - | - | - | - |
| Hydrazoic acid | \(\ce{HN3}\) | 2.5 × 10−5 | 4.6 | - | - | - | - | - | - |
| Hydrocyanic acid | \(\ce{HCN}\) | 6.2 × 10−10 | 9.21 | - | - | - | - | - | - |
| Hydrofluoric acid | \(\ce{HF}\) | 6.3 × 10−4 | 3.20 | - | - | - | - | - | - |
| Hydrogen peroxide | \(\ce{HOOH}\) | 2.0 × 10−12 | 11.7 | ||||||
| Hydrogen selenide | \(\ce{H2Se}\) | 1.3 × 10−4 | 3.89 | 1.0× 10−11 | 11.0 | - | - | - | - |
| Hydrogen sulfide | \(\ce{H2S}\) | 8.9 × 10−8 | 7.05 | 1 × 10−19 | 19 | - | - | - | - |
| Hydrogen telluride | \(\ce{H2Te}\) | 2.5 × 10−3‡ | 2.6‡ | 1 × 10−11 | 11 | - | - | - | - |
| Hypobromous acid | \(\ce{HBrO}\) | 2.8 × 10−9 | 8.55 | - | - | - | - | - | - |
| Hypochlorous acid | \(\ce{HClO}\) | 4.0 × 10−8 | 7.40 | - | - | - | - | - | - |
| Hypoiodous acid | \(\ce{HIO}\) | 3.2 × 10−11 | 10.5 | - | - | - | - | - | - |
| Iodic acid | \(\ce{HIO3}\) | 1.7 × 10−1 | 0.78 | - | - | - | - | - | - |
| Iodoacetic acid | \(\ce{CH2ICO2H}\) | 6.6 × 10−4 | 3.18 | - | - | - | - | - | - |
| Nitrous acid | \(\ce{HNO2}\) | 5.6 × 10−4 | 3.25 | - | - | - | - | - | - |
| Oxalic acid | \(\ce{C2H2O4}\) | 5.6 × 10−2 | 1.25 | 1.5 × 10−4 | 3.81 | - | - | - | - |
| Periodic acid | \(\ce{HIO4}\) | 2.3 × 10−2 | 1.64 | - | - | - | - | - | - |
| Phenol | \(\ce{C6H5OH}\) | 1.0 × 10−10 | 9.99 | - | - | - | - | - | - |
| Phosphoric acid | \(\ce{H3PO4}\) | 6.9 × 10−3 | 2.16 | 6.2 × 10−8 | 7.21 | 4.8 × 10−13 | 12.32 | - | - |
| Phosphorous acid | \(\ce{H3PO3}\) | 5.0 × 10−2* | 1.3* | 2.0 × 10−7* | 6.70* | - | - | - | - |
| Pyrophosphoric acid | \(\ce{H4P2O7}\) | 1.2 × 10−1 | 0.91 | 7.9 × 10−3 | 2.10 | 2.0 × 10−7 | 6.70 | 4.8 × 10−10 | 9.32 |
| Resorcinol | \(\ce{C6H4(OH)2}\) | 4.8 × 10−10 | 9.32 | 7.9 × 10−12 | 11.1 | - | - | - | - |
| Selenic acid | \(\ce{H2SeO4}\) | Strong | Strong | 2.0 × 10−2 | 1.7 | - | - | - | - |
| Selenious acid | \(\ce{H2SeO3}\) | 2.4 × 10−3 | 2.62 | 4.8 × 10−9 | 8.32 | - | - | - | - |
| Sulfuric acid | \(\ce{H2SO4}\) | Strong | Strong | 1.0 × 10−2 | 1.99 | - | - | - | - |
| Sulfurous acid | \(\ce{H2SO3}\) | 1.4 × 10−2 | 1.85 | 6.3 × 10−8 | 7.2 | - | - | - | - |
| meso-Tartaric acid | \(\ce{C4H6)O6}\) | 6.8 × 10−4 | 3.17 | 1.2 × 10−5 | 4.91 | - | - | - | - |
| Telluric acid | \(\ce{H2TeO4}\) | 2.1 × 10−8‡ | 7.68‡ | 1.0 × 10−11‡ | 11.0‡ | - | - | - | - |
| Tellurous acid | \(\ce{H2TeO3}\) | 5.4 × 10−7 | 6.27 | 3.7 × 10−9 | 8.43 | - | - | - | - |
| Trichloroacetic acid | \(\ce{CCl3CO2H}\) | 2.2 × 10−1 | 0.66 | - | - | - | - | - | - |
| Trifluoroacetic acid | \(\ce{CF3CO2H}\) | 3.0 × 10−1 | 0.52 | - | - | - | - | - | - |
| * Measured at 20°C, not 25°C. | |||||||||
| ‡ Measured at 18°C, not 25°C. | |||||||||
Source of data: CRC Handbook of Chemistry and Physics, 84th Edition (2004).