Skip to main content

Registration is now open for this year's LibreFest! Join us virtually the week of July 13.

Register here
Chemistry LibreTexts

16.11: Acid Dissociation Constants

  1. Last updated
  2. Save as PDF
  • Page ID
    134796

    • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \( \newcommand{\dsum}{\displaystyle\sum\limits} \)

    \( \newcommand{\dint}{\displaystyle\int\limits} \)

    \( \newcommand{\dlim}{\displaystyle\lim\limits} \)

    \( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)

    ( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\id}{\mathrm{id}}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\kernel}{\mathrm{null}\,}\)

    \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\)

    \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\)

    \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    \( \newcommand{\vectorA}[1]{\vec{#1}}      % arrow\)

    \( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

    \( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vectorC}[1]{\textbf{#1}} \)

    \( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)

    \( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)

    \( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)

    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \(\newcommand{\longvect}{\overrightarrow}\)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)

    The following table provides pKa and Ka values for selected weak acids. All values are from Martell, A. E.; Smith, R. M. Critical Stability Constants, Vols. 1–4. Plenum Press: New York, 1976. Unless otherwise stated, values are for 25 oC and for zero ionic strength. Those values in brackets are considered less reliable.

    Weak acids are arranged alphabetically by the names of the neutral compounds from which they are derived. In some cases—such as acetic acid—the compound is the weak acid. In other cases—such as for the ammonium ion—the neutral compound is the conjugate base. Chemical formulas or structural formulas are shown for the fully protonated weak acid. Successive acid dissociation constants are provided for polyprotic weak acids; where there is ambiguity, the specific acidic proton is identified.

    To find the Kb value for a conjugate weak base, recall that

    \[K_\text{a} \times K_\text{b} = K_\text{w} \nonumber\]

    for a conjugate weak acid, HA, and its conjugate weak base, A–.

    compound conjugate acid pKa Ka
    acetic acid \(\ce{CH3COOH}\) 4.757 \(1.75 \times 10^{-5}\)
    adipic acid
    adipic acid, IUPAC name: hexanedioic acid, SMILES: OC(=O)CCCCC(O)=O

    4.42

    5.42

    \(3.8 \times 10^{-5}\)

    \(3.8 \times 10^{-6}\)
    alanine alanine, IUPAC name: (2S)-2-aminopropanoic acid, SMILES: C[C@H](N)C(O)=O

    2.348 (\(\ce{COOH}\))

    9.867 (\(\ce{NH3}\))

    \(4.49 \times 10^{-3}\)

    \(1.36 \times 10^{-10}\)
    aminobenzene aminobenzene, IUPAC name: Aniline, SMILES: Nc1ccccc1 4.601 \(2.51 \times 10^{-5}\)
    4-aminobenzene sulfonic acid 4-aminobenzene sulfonic acid, IUPAC name: 4-Aminobenzenesulfonic acid, SMILES: Nc1ccc(cc1)[S](O)(=O)=O 3.232 \(5.86 \times 10^{-4}\)
    2-aminobenzoic acid
    2-aminobenzoic acid, IUPAC name: 2-aminobenzoic acid, SMILES: Nc1ccccc1C(O)=O

    2.08 (\(\ce{COOH}\))

    4.96 (\(\ce{NH3}\))

    \(8.3 \times 10^{-3}\)

    \(1.1 \times 10^{-5}\)
    2-aminophenol (\(T = 20 \text{°C}\)) 2-aminophenol, IUPAC name: 2-Aminophenol, SMILES: Nc1ccccc1O

    4.78 (\(\ce{NH3}\))

    9.97 (OH)

    \(1.7 \times 10^{-5}\)

    \(1.05 \times 10^{-10}\)
    ammonia \(\ce{NH4+}\) 9.244 \(5.70 \times 10^{-10}\)
    arginine
    arginine, IUPAC name: 2-amino-5-(diaminomethylideneamino)pentanoic acid, SMILES: N[C@@H](CCCNC(N)=N)C(O)=O

    1.823 (COOH)

    8.991 (\(\ce{NH3}\))

    [12.48] (\(\ce{NH2}\))

    \(1.50 \times 10^{-2}\)

    \(1.02 \times 10^{-9}\)

    [\(3.3 \times 10^{-13}\)]
    arsenic acid \(\ce{H3AsO4}\)

    2.24

    6.96

    11.50

    \(5.8 \times 10^{-3}\)

    \(1.1 \times 10^{-7}\)

    \(3.2 \times 10^{-12}\)
    asparagine (\(\mu = 0.1 \text{ M}\)) asparagine, IUPAC name: (2S)-2,4-diamino-4-oxobutanoic acid, SMILES: C([C@@H](C(=O)O)N)C(=O)N

    2.14 (COOH)

    8.72 (\(\ce{NH3}\))

    \(7.2 \times 10^{-3}\)

    \(1.9 \times 10^{-9}\)
    aspartic acid aspartic acid, IUPAC name: (2S)-2-aminobutanedioic acid, SMILES: N[C@@H](CC(O)=O)C(O)=O

    1.990 (\(\alpha\)-COOH)

    3.900 (\(\beta\)-COOH)

    10.002 (\(\ce{NH3}\))

    \(1.02 \times 10^{-2}\)

    \(1.26 \times 10^{-4}\)

    \(9.95 \times 10^{-11}\)
    benzoic acid benzoic acid, IUPAC name: benzoic acid, SMILES: OC(=O)c1ccccc1 4.202 \(6.28 \times 10^{-5}\)
    benzylamine benzylamine, IUPAC name: phenylmethanamine, SMILES: NCc1ccccc1 9.35 \(4.5 \times 10^{-10}\)
    boric acid (\(pK_\text{a2}, pK_\text{a3: } T = 20 \text{°C}\)) \(\ce{H3BO3}\)

    9.236

    [12.74]

    [13.80]

    \(5.81 \times 10^{-10}\)

    [\(1.82 \times 10^{-13}\)]

    [\(1.58 \times 10^{-14}\)]
    carbonic acid \(\ce{H2CO3}\)

    6.352

    10.329

    \(4.45 \times 10^{-7}\)

    \(4.69 \times 10^{-11}\)
    catechol catechol, IUPAC name: benzene-1,2-diol, SMILES: Oc1ccccc1O

    9.40

    12.8

    \(4.0 \times 10^{-10}\)

    \(1.6 \times 10^{-13}\)
    chloracetic acid \(\ce{ClCH2COOH}\) 2.865 \(1.36 \times 10^{-3}\)
    chromic acid (\(pK_\text{a1: } T = 20 \text{°C}\)) \(\ce{H2CrO4}\)

    –0.2

    6.51

    1.6

    \(3.1 \times 10^{-7}\)
    citric acid citric acid, IUPAC name: 2-hydroxypropane-1,2,3-tricarboxylic acid, SMILES: OC(=O)CC(O)(CC(O)=O)C(O)=O

    3.128 (COOH)

    4.761 (COOH)

    6.396 (COOH)

    \(7.45 \times 10^{-4}\)

    \(1.73 \times 10^{-5}\)

    \(4.02 \times 10^{-7}\)
    cupferron (\(\mu = 0.1 \text{ M}\)) cupferron, IUPAC name: azane; N-hydroxy-N-phenylnitrous amide, SMILES: N.ON(N=O)c1ccccc1 4.16 \(6.9 \times 10^{-5}\)
    cysteine cysteine, IUPAC name: (2R)-2-amino-3-sulfanylpropanoic acid, SMILES: N[C@@H](CS)C(O)=O

    [1.71] (COOH)

    8.36 (SH)

    10.77 (\(\ce{NH3}\))

    [\(1.9 \times 10^{-2}\)]

    \(4.4 \times 10^{-9}\)

    \(1.7 \times 10^{-11}\)
    dichloracetic acid \(\ce{Cl2CHCOOH}\) 1.30 \(5.0 \times 10^{-2}\)
    diethylamine \(\ce{(CH3CH2)2NH2+}\) 10.933 \(1.17 \times 10^{-11}\)
    dimethylamine \(\ce{(CH3)2NH2+}\) 10.774 \(1.68 \times 10^{-11}\)
    dimethylglyoxime dimethylglyoxime, IUPAC Name: N-(3-hydroxyiminobutan-2-ylidene)hydroxylamine SMILES: CC(=NO)C(=NO)C

    10.66

    12.0

    \(2.2 \times 10^{-11}\)

    \(1. \times 10^{-12}\)
    ethylamine \(\ce{CH3CH2NH3+}\) 10.636 \(2.31 \times 10^{-11}\)
    ethylenediamine \(\ce{+H3NCH2CH2NH3+}\)

    6.848

    9.928

    \(1.42 \times 10^{-7}\)

    \(1.18 \times 10^{-10}\)

    ethylenediaminetetracetic acid

    (EDTA) (\(\mu = 0.1 \text{ M}\))

    		 ethylenediaminetetracetic acid, IUPAC name: 2-[2-(bis(carboxymethyl)amino)ethyl-(carboxymethyl)amino]acetic acid, SMILES: OC(=O)CN(CCN(CC(O)=O)CC(O)=O)CC(O)=O

    0.0 (COOH)

    1.5 (COOH)

    2.0 (COOH)

    2.66 (COOH)

    6.16 (NH)

    10.24 (NH)

    1.0

    \(3.2 \times 10^{-2}\)

    \(1.0 \times 10^{-2}\)

    \(2.2 \times 10^{-3}\)

    \(6.9 \times 10^{-7}\)

    \(5.8 \times 10^{-11}\)
    formic acid \(\ce{HCOOH}\) 3.745 \(1.80 \times 10^{-4}\)
    fumaric acid fumaric acid, IUPAC name: But-2-enedioic acid, SMILES: OC(=O)/C=C/C(O)=O

    3.053

    4.494

    \(8.85 \times 10^{-4}\)

    \(3.21 \times 10^{-5}\)
    glutamic acid
    glutamic acid, IUPAC name: (2S)-2-aminopentanedioic acid, SMILES: N[C@@H](CCC(O)=O)C(O)=O

    2.33 (\(\alpha\)-COOH)

    4.42 (\(\lambda\)-COOH)

    9.95 (\(\ce{NH3}\))

    \(5.9 \times 10^{-3}\)

    \(3.8\times 10^{-5}\)

    \(1.12 \times 10^{-10}\)
    glutamine glutamine, IUPAC name: (2S)-2,5-diamino-5-oxopentanoic acid, SMILES: N[C@@H](CCC(N)=O)C(O)=O

    2.17 (COOH)

    9.01 (\(\ce{NH3}\))

    \(6.8 \times 10^{-3}\)

    \(9.8 \times 10^{-10}\)
    glycine glycine, IUPAC Name: 2-aminoacetic acid SMILES: C(C(=O)O)N

    2.350 (COOH)

    9.778 (\(\ce{NH3}\))

    \(4.47 \times 10^{-3}\)

    \(1.67 \times 10^{-10}\)
    glycolic acid \(\ce{HOOCH2COOH}\)

    3.881 (COOH)

    		 \(1.48 \times 10^{-4}\)
    histidine (\(\mu = 0.1 \text{ M}\)) histidine, IUPAC name: 2-amino-3-(3H-imidazol-4-yl)propanoic acid, SMILES: N[C@@H](Cc1c[nH]cn1)C(O)=O

    1.7 (COOH)

    6.02 (NH)

    9.08 (\(\ce{NH3}\))

    \(2. \times 10^{-2}\)

    \(9.5 \times 10^{-7}\)

    \(8.3 \times 10^{-10}\)
    hydrogen cyanide \(\ce{HCN}\) 9.21 \(6.2 \times 10^{-10}\)
    hydrogen fluroride \(\ce{HF}\) 3.17 \(6.8 \times 10^{-4}\)
    hydrogen peroxide \(\ce{H2O2}\) 11.65 \(2.2 \times 10^{-12}\)
    hydrogen sulfide \(\ce{H2S}\)

    7.02

    13.9

    \(9.5 \times 10^{-8}\)

    \(1.3 \times 10^{-14}\)
    hydrogen thiocyanate \(\ce{HSCN}\) 0.9 \(1.3 \times 10^{-1}\)
    8-hydroxyquinoline 8-hydroxyquinoline, IUPAC name: quinolin-8-ol, SMILES: Oc1cccc2cccnc12

    4.9 (NH)

    9.81 (OH)

    \(1.2 \times 10^{-5}\)

    \(1.6 \times 10^{-10}\)
    hydroxylamine \(\ce{HONH3+}\) 5.96 \(1.1 \times 10^{-6}\)
    hypobromous acid \(\ce{HOBr}\) 8.63 \(2.3 \times 10^{-9}\)
    hypochlorous acid \(\ce{HOCl}\) 7.53 \(3.0\times 10^{-8}\)
    hypoiodous acid \(\ce{HOI}\) 10.64 \(2.3 \times 10^{-11}\)
    iodic acid \(\ce{HIO3}\) 0.77 \(1.7 \times 10^{-1}\)
    isoleucine
    isoleucine, IUPAC name: (2S,3S)-2-Amino-3-methylpentanoic acid, SMILES: CC[C@H](C)[C@H](N)C(O)=O

    2.319 (COOH)

    9.754 (\(\ce{NH3}\))

    \(4.8 \times 10^{-3}\)

    \(1.76 \times 10^{-10}\)
    leucine leucine, IUPAC name: (2S)-2-amino-4-methylpentanoic acid, SMILES: CC(C)C[C@H](N)C(O)=O

    2.329 (COOH)

    9.747 (\(\ce{NH3}\))

    \(4.69 \times 10^{-3}\)

    \(1.79 \times 10^{-10}\)
    lysine (\(\mu = 0.1 \text{ M}\)) lysine, IUPAC name: (2S)-2,6-diaminohexanoic acid, SMILES: NCCCC[C@H](N)C(O)=O

    2.04 (COOH)

    9.08 (\(\alpha \text{-} \ce{NH3}\))

    10.69 (\(\epsilon \text{-} \ce{NH3}\))

    \(9.1 \times 10^{-3}\)

    \(8.3 \times 10^{-10}\)

    \(2.0 \times 10^{-11}\)
    maleic acid maleic acid, IUPAC name: But-2-enedioic acid, SMILES: OC(=O)\C=C/C(O)=O

    1.910

    6.332

    \(1.23 \times 10^{-2}\)

    \(4.66 \times 10^{-7}\)
    malic acid malic acid, IUPAC name: 2-Hydroxybutanedioic acid, SMILES: OC(CC(O)=O)C(O)=O

    3.459 (COOH)

    5.097 (COOH)

    \(3.48 \times 10^{-4}\)

    \(8.00 \times 10^{-6}\)
    malonic acid \(\ce{HOOCCH2COOH}\)

    2.847

    5.696

    \(1.42 \times 10^{-3}\)

    \(2.01 \times 10^{-6}\)
    methionine (\(\mu = 0.1 \text{ M}\)) methionine, IUPAC name: (2S)-2-amino-4-methylsulfanylbutanoic acid, SMILES: CSCC[C@H](N)C(O)=O

    2.20 (COOH)

    9.05 (\(\ce{NH3}\))

    \(6.3 \times 10^{-3}\)

    \(8.9 \times 10^{-10}\)
    methylamine \(\ce{CH3NH3+}\) 10.64 \(2.3 \times 10^{-11}\)
    2-methylaniline 2-methylaniline, IUPAC Name: 2-methylaniline SMILES: CC1=CC=CC=C1N 4.447 \(3.57 \times 10^{-5}\)
    4-methylaniline 4-methylaniline, IUPAC Name: 4-methylaniline SMILES: CC1=CC=C(C=C1)N 5.084 \(8.24 \times 10^{-6}\)
    2-methylphenol 2-methylphenol, IUPAC name: 2-Methylphenol, SMILES: Cc1ccccc1O 10.28 \(5.2 \times 10^{-11}\)
    4-methylphenol 4-methylphenol, IUPAC name: 4-Methylphenol, SMILES: Cc1ccc(O)cc1 10.26 \(5.5 \times 10^{-11}\)

    nitrilotriacetic acid

    (\(T = 20 \text{°C}), pK_\text{a1: } \mu = 0.1 \text{ M}\))

    		 nitrilotriacetic acid, IUPAC name: 2-(bis(carboxymethyl)amino)acetic acid, SMILES: OC(=O)CN(CC(O)=O)CC(O)=O

    1.1 (COOH)

    1.650 (COOH)

    2.940 (COOH)

    10.334 (\(\ce{NH3}\))

    \(8. \times 10^{-2}\)

    \(2.24 \times 10^{-2}\)

    \(1.15 \times 10^{-3}\)

    \(4.63 \times 10^{-11}\)
    2-nitrobenzoic acid 2-nitrobenzoic acid, IUPAC name: 2-Nitrobenzoic acid, SMILES: OC(=O)c1ccccc1[N+]([O-])=O 2.179 \(6.62 \times 10^{-3}\)
    3-nitrobenzoic acid 3-nitrobenzoic acid, IUPAC name: 3-Nitrobenzoic acid, SMILES: OC(=O)c1cccc(c1)[N+]([O-])=O 3.449 \(3.56 \times 10^{-4}\)
    4-nitrobenzoic acid 4-nitrobenzoic acid, IUPAC name: 4-Nitrobenzoic acid, SMILES: OC(=O)c1ccc(cc1)[N+]([O-])=O 3.442 \(3.61 \times 10^{-4}\)
    2-nitrophenol 2-nitrophenol, IUPAC Name: 2-nitrophenol SMILES: C1=CC=C(C(=C1)[N+](=O)[O-])O 7.21 \(6.2 \times 10^{-8}\)
    3-nitrophenol
    3-nitrophenol, IUPAC name: 3-Nitrophenol, SMILES: Oc1cccc(c1)[N+]([O-])=O    		 8.39 \(4.1 \times 10^{-9}\)
    4-nitrophenol 4-nitrophenol, IUPAC name: 4-Nitrophenol, SMILES: Oc1ccc(cc1)[N+]([O-])=O 7.15 \(7.1 \times 10^{-8}\)
    nitrous acid \(\ce{HNO2}\) 3.15 \(7.1 \times 10^{-4}\)
    oxalic acid \(\ce{H2C2O4}\)

    1.252

    4.266

    \(5.60 \times 10^{-2}\)

    \(5.42 \times 10^{-5}\)
    1,10-phenanthroline 1,10-phenanthroline, IUPAC name: 1,10-phenanthroline, SMILES: C1=CC2=C(C3=C(C=CC=N3)C=C2)N=C1 4.86 \(1.38 \times 10^{-5}\)
    phenol phenol, IUPAC name: PHENOL, SMILES: Oc1ccccc1 9.98 \(1.05 \times 10^{-10}\)
    phenylalanine phenylalanine, IUPAC name: (2S)-2-amino-3-phenylpropanoic acid, SMILES: N[C@@H](Cc1ccccc1)C(O)=O

    2.20 (COOH)

    9.31 (\(\ce{NH3}\))

    \(6.3 \times 10^{-3}\)

    \(4.9 \times 10^{-10}\)
    phosphoric acid \(\ce{H3PO4}\)

    2.148

    7.199

    12.35

    \(7.11 \times 10^{-3}\)

    \(6.32 \times 10^{-8}\)

    \(4.5 \times 10^{-13}\)
    phthalic acid phthalic acid, IUPAC name: phthalic acid, SMILES: OC(=O)c1ccccc1C(O)=O

    2.950

    5.408

    \(1.12 \times 10^{-3}\)

    \(3.91 \times 10^{-6}\)
    piperidine piperidine, IUPAC Name: piperidine, SMILES: C1CCNCC1 11.123 \(7.53 \times 10^{-12}\)
    proline proline, IUPAC name: (2S)-pyrrolidine-2-carboxylic acid, SMILES: OC(=O)[C@@H]1CCCN1

    1.952 (COOH)

    10.650 (NH)

    \(1.12 \times 10^{-2}\)

    \(2.29 \times 10^{-11}\)
    propanoic acid \(\ce{CH3CH2COOH}\)

    4.874

    		 \(1.34 \times 10^{-5}\)
    propylamine \(\ce{CH3CH2CH2NH3+}\) 10.566 \(2.72 \times 10^{-11}\)
    pyridine pyridine, IUPAC name: Pyridine, SMILES: c1ccncc1 5.229 \(5.90 \times 10^{-6}\)
    resorcinol resorcinol, IUPAC name: benzene-1,3-diol, SMILES: Oc1cccc(O)c1

    9.30

    11.06

    \(5.0 \times 10^{-10}\)

    \(8.7 \times 10^{-12}\)
    salicylic acid salicylic acid, IUPAC name: 2-Hydroxybenzoic acid, SMILES: OC(=O)c1ccccc1O

    2.97 (COOH)

    13.74 (OH)

    \(1.1 \times 10^{-3}\)

    \(1.8 \times 10^{-14}\)
    serine serine, IUPAC name: (2S)-2-amino-3-hydroxypropanoic acid, SMILES: N[C@@H](CO)C(O)=O

    2.187 (COOH)

    9.209 (\(\ce{NH3}\))

    \(6.50 \times 10^{-3}\)

    \(6.18 \times 10^{-10}\)
    succinic acid succinic acid, IUPAC name: butanedioic acid, SMILES: OC(=O)CCC(O)=O

    4.207

    5.636

    \(6.21 \times 10^{-5}\)

    \(2.31 \times 10^{-6}\)
    sulfuric acid \(\ce{H2SO4}\)

    strong

    1.99

    —

    \(1.0 \times 10^{-2}\)
    sulfurous acid \(\ce{H2SO3}\)

    1.91

    7.18

    \(1.2 \times 10^{-2}\)

    \(6.6 \times 10^{-8}\)
    D-tartaric acid D-tartaric acid, IUPAC name: (2S,3S)-2,3-dihydroxybutanedioic acid, SMILES: O[C@@H]([C@H](O)C(O)=O)C(O)=O

    3.036 (COOH)

    4.366 (COOH)

    \(9.20 \times 10^{-4}\)

    \(4.31 \times 10^{-5}\)
    threonine threonine, IUPAC name: (2S,3R)-2-amino-3-hydroxybutanoic acid, SMILES: C[C@@H](O)[C@H](N)C(O)=O

    2.088 (COOH)

    9.100 (\(\ce{NH3}\))

    \(8.17 \times 10^{-3}\)

    \(7.94 \times 10^{-10}\)
    thiosulfuric acid \(\ce{H2S2O3}\)

    0.6

    1.6

    \(3. \times 10^{-1}\)

    \(3. \times 10^{-2}\)
    trichloracetic acid (\(\mu = 0.1 \text{ M}\)) \(\ce{Cl3CCOOH}\) 0.66 \(2.2 \times 10^{-1}\)
    triethanolamine \(\ce{(HOCH2CH2)3NH+}\) 7.762 \(1.73 \times 10^{-8}\)
    triethylamine \(\ce{(CH3CH2)3NH+}\) 10.715 \(1.93 \times 10^{-11}\)
    trimethylamine \(\ce{(CH3)3NH+}\) 9.800 \(1.58 \times 10^{-10}\)
    tris(hydroxymethyl)amino methane (TRIS or THAM) \(\ce{(HOCH2)3CNH3+}\) 8.075 \(8.41 \times 10^{-9}\)
    tryptophan (\(\mu = 0.1 \text{ M}\))
    tryptophan, IUPAC name: (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid, SMILES: N[C@@H](Cc1c[nH]c2ccccc12)C(O)=O

    2.35 (COOH)

    9.33 (\(\ce{NH3}\))

    \(4.5 \times 10^{-3}\)

    \(4.7 \times 10^{-10}\)
    tyrosine (\(pK_\text{a1: } \mu = 0.1 \text{ M}\)) tyrosine, IUPAC name: (2S)-2-amino-3-(4-hydroxyphenyl)propanoic acid, SMILES: N[C@@H](Cc1ccc(O)cc1)C(O)=O

    2.17 (COOH)

    9.19 (\(\ce{NH3}\))

    10.47 (OH)

    \(6.8 \times 10^{-3}\)

    \(6.5 \times 10^{-10}\)

    \(3.4 \times 10^{-11}\)
    valine valine, IUPAC name: (2S)-2-amino-3-methylbutanoic acid, SMILES: CC(C)[C@H](N)C(O)=O

    2.286 (COOH)

    9.718 (\(\ce{NH3}\))

    \(5.18 \times 10^{-3}\)

    \(1.91 \times 10^{-10}\)

    16.11: Acid Dissociation Constants is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.