Pka values table. 3O+have been experimentally determined to be 14.

Pka values table a. pK a is the negative logarithm of the acid dissociation constant, K a, which can be measured experimentally. Definitions of the acid dissociation constant and pKa are given below the table. All values are from Martell, A. Pka is the negative logarithm of Ka. 1 Biochemistry, Seventh Edition 2012 W. . The document presents tables of pKa values for various inorganic acids, carboxylic acids, alcohols, and protonated species in both water and DMSO. peptideweb. 2946 Looking at Table 5 2 1, you see that the pK a of carboxylic acids are in the 4-5 range, the pK a of sulfuric acid is –10, and the pK a of water is 14. The strength of a base is related to the pK a of its conjugate acid as pK b = 14 - pK a. Table 1 3 1 1: Representative acid constants pKa values in organic chemistry – making maximum use of the available data Agnes Kütt, Sigrid Selberg, Ivari Kaljurand, Sofja Tshepelevitsh, Agnes Heering, Astrid Mar 31, 2025 · Discover various methods to determine pKa values, including titration, UV-Vis spectroscopy, NMR, HPLC, and the Henderson-Hasselbalch equation. Read these instructions to learn how to use this acids and bases chart. Learn the principles, procedures, and applications of each technique for accurate pKa determination. e. pK Organic Chemistry Acid-Base Chemistry How to Estimate the pKa Values Using the pKa Table In the realm of organic chemistry, understanding acid-base reactions is paramount. This document provides tables of pKa values for various acids and acid-containing compounds in water and DMSO. 4×10–5 Arsenic acid H3AsO4 6. ; Smith, R. pKa values of amino acids Star Republic: Guide for Biologists Mar 13, 2018 · Converting to pKa Ka values can be very large or very small. Jan 16, 2025 · Looking at Table 1 3 1 1, you see that the pK a of carboxylic acids are in the 4-5 range, the pK a of sulfuric acid is –10, and the pK a of water is 14. pKa values range from approximately -14 to 53, with Jun 8, 2025 · Learn how to calculate acidity constants (pKa) in organic compounds to predict their behavior, stability, and reactivity in chemical reactions. color change for acid and base indicators - together with pKa and structures of the indicators. 1 and Table 16. 5 Group Terminal a-carboxyl group Aspartic acid Glutamic acid Histidine Terminal a-amino group Cysteine Tyrosine Lysine Arginine Acid Base *pKa values depend on temperature, ionic strength, and the microenvironment of the ionizable group. 5 27. For reference or additional information, please contact websupport@aatbio. Alfa Chemistry has listed typical pKa ranges for different classes of amines, diamines, and cyclic nitrogen compounds in the table below for reference only. Chem. For example, the Ka value for hydrochloric acid (HCl) is around 10 7, while the Ka value for ascorbic acid (vitamin C) is 1. 8 and/or from the Reference Tables to determine if the following reactions would be expected to occur: a) b) c) Answer a) Yes - alkenes have pK a values of ~35 while alkynes have pK a values of ~25. 2. 74 Oct 27, 2016 · At the beginning of the lecture, I present the pK a values, based on Table 6-1, to the class and explain the trends of the various functional groups and ionizable protons. Here are some typical pKa values describing the acidities of common carbonyls that we usually see in organic chemistry. Amino acid pK (or pKa) values describe the ionization behavior of ionizable groups found in proteins. 74, respectively are erroneous numbers proposed by scientists who made some errors in the calculated “rational” values. Table 1 3 1 1: Representative acid constants Mar 31, 2025 · Discover various methods to determine pKa values, including titration, UV-Vis spectroscopy, NMR, HPLC, and the Henderson-Hasselbalch equation. We may be able to help! The highlighted papers contain large amounts of p Ka data (or other information): acids – red, bases – blue, both acids and bases – purple. For graphical plots of a large number of substituted phosphorus triphosphate tetrametaphosphate 8. These groups are the carboxylic acids of the carboxyl terminus, aspartic acid and glutamic acid, the imidazole ring of histidine, the α-amino group at the amino terminus, the sulfhydryl group of cysteine, the phenolic group of tyrosine, the amino group of lysine and the guanidino group of Downloads expand_more Download Page (PDF) Download Full Book (PDF) Resources expand_more Periodic Table Physics Constants Scientific Calculator Reference expand_more Reference & Cite Tools expand_more Note; The pKa values associated with bases is normally meant to refer to the true pKa's of their conjugate acids; i. Chem 344 – University of Wisconsin Table of pKa valuesa of acids in different solvents from http://dx. 0×10–7 HAsO42– 3. To navigate this complex field, chemists often turn to pKa tables as indispensable tools. Chim. Recall that pKa is equal to the negative logarithm of the Ka. These groups are the carboxylic acids of the carboxyl terminus, aspartic acid and glutamic acid, the imidazole ring of histidine, the α-amino group at the amino terminus, the sulfhydryl group of cysteine, the phenolic group of tyrosine, the amino group of lysine and the guanidino group of Figure 3. For comprehensive pKa information, please visit Bordwell pKa Table. and 2) J. Oct 5, 2021 · Get the definition of pKa in chemistry and understand how it relates to the acid dissociation constant Ka and the strength of acids. E. 00 . Acids with a K a value less than one are considered weak and get weaker as we move to the bottom of the table. Page 1 pKa Data Compiled by R. All data apply to dilute aqueous solutions and are presented in the form of pK a, which is the negative of the logarithm of the acid dissociation constant K a. P. 3. Unless otherwise stated, values are for 25 o C and for zero ionic strength. the higher its acidity constant K a), the lower its pK a value, and viceversa. Figure TD7. Table 2. com The Essential pKa Values: students should memorize these values on page 1 strong acid (pKa < 0) *Values <0 for H2O and DMSO, and values >14 for water and >35 for DMSO were extrapolated using various methods. Adding the two pK a values together and dividing by 2 gives us a value of 5. Alkenes and alkanes, which are not acidic at all, have pK a values above 30. 9 pKa values of common compounds and their conjugate bases ChemistrySteps. Understanding the proper use of a pKa table will give you the ability to recognize which acid-base reactions will happen and which will not. pKa values indicate the pH at which an acid is half dissociated into its conjugate base. So, I want to emphasize how important it is to become familiar with your pKa table. It forms the foundation for comprehending a myriad of chemical processes. ciently soluble. pKa tables don't always match exactly between different sources because pKa values are determined experimentally, and different laboratories use slightly different conditions. pK a values for some organic (and other) acids. Acta2014, 97, 1. 2, respectively, and a more extensive set of data is provided in Tables E1 and E2. Because of the use of negative logarithms, smaller values of \ (pK_a\) correspond to larger acid ionization constants and hence stronger acids. The table is organised into columns of compounds. These tables are compiled in PDF files below. The ε -amino group of lysine (Lys, K) has an intrinsic pK value of 11. pKa TableTable of pKa values of inorganic acid, organic acid, hydrocarbon, amine, amide, etc. a) HNO 3 or HNO 2 b) H 2 Se or H 2 O c) HCl or H 2 SO4 d) Be (OH) 2 or HSeO 3 The stronger the acid (i. Table 1. This means that alkynes are more acidic and more likely to donate a proton. This table lists the acid-base dissociation constants of over 600 organic compounds, including many amino acids. Unless otherwise stated, pKa and pKb was measured at STP. 9 10. pKa is the negative log base ten of the Ka value, to be precise (acid dissociation constant). We present a new version of PKAD, named PKAD-R, which is a curated database of experimentally determined protein pKa values. Table of Acids With K and pK Values a a The values of \ (pK_a\) and \ (pK_b\) are given for several common acids and bases in Table 16. See: 1) Helv. For strengths of organic acids see E. What is pKa? The pKa value is the negative base -10 logarithm of the acid dissociation constant (Ka) of a solution. a) HNO 3 or HNO 2 b) H 2 Se or H 2 O c) HCl or H 2 SO4 d) Be (OH) 2 or HSeO 3 Use table search to locate desired compound in database. Values for the negative logarithm of the acid dissociation constant, pKa, of the conjugated acid of amines, diamines and cyclic organic nitrogen compounds, shown together with the molecular structure of the acids. This is crucial for understanding the charge state of amino acids at different pH levels and predicting their behavior in proteins. Dempsey (eds. One possible classification relevant for acid-base chemistry is presented in Table 1. 6×10–10 Ascorbic acid H2C6H6O6 6. The tables are organized by functional groups including inorganic acids, alcohols, carboxylic acids, amines, amides, and others. Most instructors will provide you with some sort of a pKa table on the exam. The pK a value listed next to the compound is an index of how tightly that hydrogen is held by the The pKa table is one big mystery for a lot of organic chemistry students. Mar 31, 2025 · The table above presents representative pKa values for common organic acids. pKa values range from approximately -14 to 53. Study with Quizlet and memorize flashcards containing terms like Estimate the net charge at pH=7pH=7. Jan 25, 2013 · I love the pKa table. The pKa values for organic acids can be found in Appendix II of Bruice 5th Ed. Classification of organic solvents based on their acid-base behavior [6], [7]. The strongest bases are around pH 14-15 and some of the weakest bases have pKa values around 35 and higher. 97 for the isoelectric point. Values for the negative logarithm of the acid dissociation constant, pKa, of inorganic acids and bases, as well as hydrated metal ions. Earlier values of 15. These are established reference values in many books Problem AB9. Not knowing pKa values in organic chemistry is like not knowing the value of the hands in poker. Working with such numbers is inconvenient, so to makes things easier, chemists have defined the pKa number as: pKa = -log Ka According to this definition, the pKa value for hydrochloric acid is -log Oct 6, 2025 · This pH to pKa or pKa Calculator is designed for students, chemists, and researchers to find the pKa value using the Henderson-Hasselbalch equation. A wide range of functional groups are We would like to show you a description here but the site won’t allow us. 8×10–5 HC6H6O6– 2. The table lists the K a values and the strength of each acid and base. Table 3. , pKa associated with HO- is 15. 1. pKa = -log (Ka) HB Ka H+ + B– the smaller the number, the more acidic also pKa’ is the acidity of the conjugate acid 30. If the amino acid has a side chain that also has a pKa (pKa 3 in the table above), the isoelectric point is determined by taking the average of the two closest pKa values. Tables of pK a values usually show the acids and their conjugate bases arranged by order of decreasing (or increasing) acidity. It puts chemical reactivity in perspective. Why is the pK of the carboxyl group of an amino acid so much lower than that of acetic acid (pK = 4. 5. 0 8. org/10. For your convenience, the biological buffers table contain values of pKa 0, d (pKa 0)/dt at 298. A wide range of functional groups are Feb 9, 2023 · The pK a values for glycine, for example, are 2. H. 0. Here is a table with some structures and pK a values for amino acids. 1002/poc. 4: pKa Table is shared under a not declared license and was authored, remixed, and/or curated by Sergio Cortes. The values in the table below are normalized so that the most hydrophobic residue is given a value of 100 relative to glycine, which is considered neutral (0 value). IMPORTANT: I’m not sure if your computer shows it properly, but be very careful which ones have the approximate symbol (that squiggly thing called tilde: ∼), and which ones have the negative symbol. 8)? *Values <0 for H2O and DMSO, and values >14 for water and >35 for DMSO were extrapolated using various methods. Acidity-Basicity Data (p Ka Values) in Nonaqueous Solvents (and some in water as well) If you cannot find the data that you need, please contact ivo. The document lists various compounds and their pKa values. 34 (for the carboxylic acid) and 9. Problem AB9. It determines an acid’s strength, or how tightly a proton is held by a Bronsted acid. The pKa values span a wide range, from approximately -14 to 38, depending on the substance Buffer TableBuffer Table Notice that the pKa-lowering effect of each chlorine atom, while significant, is not as dramatic as the delocalizing resonance effect illustrated by the difference in pK a values between an alcohol and a carboxylic acid. The pKa of a strong acid is less than zero. com Custom peptide synthesis | Equipment, glassware and reagents for peptide synthesis *Values <0 for H2O and DMSO, and values >14 for water and >35 for DMSO were extrapolated using various methods. 30 2. Ripin, D. 04 p Ka units). 3 26. 2017, 94, 690. All data apply to dilute aqueous solutions and are presented as values of pKa, which is defined as the negative of the logarithm of the equi-librium constant Ka for the reaction Table of pKa and pI values The pK a values and the isoelectronic point, pI, are given below for the 20 α-amino acids. One should always know which source to use. 26, 2. , Estimate the net charge at pH=12pH=12. The pKa values (theoretical and computed) of the macrocyclic glycopeptide ionizable groups, namely carboxylic acids, amines (primary and secondary), and phenolic groups are reported in Table 2. 9) N N *Values <0 for H2O and DMSO, and values >14 for water and >35 for DMSO were extrapolated using various methods. 0 10. Weak acids are arranged alphabetically by the names of the neutral Earlier values (published before 2019) changed slightly (usually by 0. As expected, such compounds display Table of pKa and pI values The pK a values and the isoelectronic point, pI, are given below for the 20 α-amino acids. b. Nov 16, 2025 · Chemical Data Info on pKa values, nucleophile/electrophiles, A-values, solvents, physical constants, etc. Table of Acids with Ka and pKa Values* Exercises Exercise 2 8 1 Use the pKa table from Section 2. The quantitative behavior of acids and bases in solution can be understood only if their pKa values are known. Fortunately, however, it is usually not necessary to know the exact p Ka values for most cases in organic chemistry, and the approximate range is good enough. The pI's of these amino acids (last column) are often very different from those noted above for the simpler members. pdf), Text File (. Chemistry students should become proficient at reading and using data presented in such tables. This is often sloppily used by organic chemists, and can lead to confusion, especially with amines. 8 12. Jul 17, 2022 · In this article, we highlight the importance of p K a values in medicinal chemistry and drug discovery and provide a reference poster of p K a values of common amines’ conjugate bases. Inorganic Acids and Bases - pKa Values Values for the negative logarithm of the acid dissociation constant, pKa, of inorganic acids and bases, as well as hydrated metal ions. Freeman and Evans PKa Table - Free download as PDF File (. 4×10–5 Ammonium ion NH4+ 5. Approximate pKa chart of the functional groups: values to know Sep 29, 2010 · A Key Skill – How To Use A pKa Table Today we’ll talk about an incredibly important skill that might take some time to grasp but pays tremendous dividends. Plenum Press: New York, 1976. 7, which is the pKa of H2O. However dealing with a difference of 60 orders of magnitude is hard on our brains. In particular, the pH of a solution can be predicted when the analytical concentration and pKa values of all acids and bases are known; conversely, it is possible to pKa and pI values of amino acids www. Comprehensive pKa table for inorganic, carboxylic, alcohols, nitrogen compounds, hydrocarbons, and other organic compounds in H2O and DMSO. 6×10–10 Anilinium ion C6H5NH3+ 1. leito [at]ut. 2 of 2) Jun 16, 2024 · The following table provides p Ka and Ka values for selected weak acids. The pKa is derived from the equilibrium constant for the acid’s dissociation reaction, Ka, and uses a logarithmic scale to allow the pKa values to span wide ranges. Many Acid Ionization Constants at 25 °C. Collection of acidity data in various non-aqueous solvents is here . ), Ionization Constants of Organic Acids in Solution, IUPAC Chemical Data Series No. D. * Compiled from Appendix 5 Chem 1A, B, C Lab Manual and Zumdahl 6th Ed. Amino Acid Data TableSee bottom of page to choose additional tables Acidity-Basicity Data (p Ka Values) in Nonaqueous Solvents (and some in water as well) If you cannot find the data that you need, please contact ivo. Acid Formula Ka Acetic acid HC2H3O2 1. Clicking the pKa value of a compound in the following table will lead to the original paper of each p Ka value. And the lower pKa value the stronger the acid. These compounds are listed in Table 26 3 1. 0 and 0. 57 57 57 **These values were obtained in 50% ethanol. May 9, 2012 · The acidity constant Ka is the equilibrium constant for dissociation of an acid into its conjugate base and H+. 0×10–3 H2AsO4– 1. 8×10–12 We would like to show you a description here but the site won’t allow us. 25 K, and a calculator that allows you to estimate pKa values of each buffer at temperatures form 3oC to 37oC, and concentrations from 1 to 500mM for "white background" buffers and 1 to 130mM for "brown background" buffers. Specific pKa values are provided for substances such as H3O+, H2O, HCl, HF, HCN, benzoic acid, methanol, phenol, and protonated amines and imines. 2×10–12 Arsenous acid H3AsO3 6. We’ve seen over and over again that a typical reaction of carbonyls is either a nucleophilic addition to aldehydes and ketones, or various acyl substitutions of carboxylic acid derivatives. , How many peptides would result if this peptide were treated with (1) cyanogen bromide, or (2) trypsin, or (3) chymotrypsin? and more. H. Use it to help you decide which of the following pairs is the most Bronsted acidic in water. In the following pKa table, molecules […] Jun 7, 2017 · II. 7 and –1. Educ. The pKa values given here are extrapolated for water at 25 ºC. 6 X 10 -12. What is its formula and significance. However, the Apr 18, 2017 · The best way to quantify the basicity of an amine is to examine the pKa of its conjugate acid, a value I refer to here as pKaH. 8×10–5 Acrylic acid HC3H3O2 5. pKa is a measure of acidity, with lower values indicating stronger acids. Sep 20, 2025 · A pKa table for amino acids lists the pKa values for the carboxyl group, amino group, and any ionizable side chains of each amino acid. Jun 18, 2010 · The importance of pK a values in organic chemistry can’t be overestimated, in my opinion. Evans PKa Table - Free download as PDF File (. 1 Typical PK values of ionizable groups in proteins Typical PK 6. Comprehensive reference on the 20 common amino acids in proteins, detailing their pKa values and properties for organic chemistry studies. The property values for several most common solvents are listed in Table 2. Williams pKa Values INDEX Inorganic 2 Phenazine 24 Phosphates 3 Pyridine 25 Carboxylic acids 4, 8 Pyrazine 26. A third pK a, representing the acidity or basicity of the extra function, is listed in the fourth column of the table. doi. Mar 21, 2013 · Provides a comprehensive table of acids with their Ka and pKa values for reference and study purposes. Com Chapter 27 Appendix C: Dissociation Constants and p Ka Values for Acids at 25°C Source of data: CRC Handbook of Chemistry and Physics, 84th Edition (2004). Table of Acid and Base Strength Table of pKa and pI values The pK a values and the isoelectronic point, pI, are given below for the 20 α-amino acids. Oct 27, 2017 · Below are tables that include determined pKa values for various acids as determined in water, DMSO and in the gas Phase. 60 (for the ammonium). Table of Acids with Ka and pKa Values* CLAS * Compiled from Appendix 5 Chem 1A, B, C Lab Manual and Zumdahl 6th Ed. The pKa value of an acid is a quantitative measurement of a molecule’s acidity. The database builds upon its predecessors, PKAD and PKAD-2, with significant updates and improvements For your convenience, the biological buffers table contain values of pKa 0, d (pKa 0)/dt at 298. If we look at those numbers, they are kind of all over the place. Jun 10, 2025 · Our table shows Ka values for weak acids, including the Ka of acetic acid, to help you understand acid strength and dissociation in aqueous solutions. A. 1–4. Those values in brackets are considered less reliable. Some of the strongest acids listed have pKa values around -10, while the weakest acids are around pH 10-11. Table of Acids With K and pK Values a a Understanding pKa values in ionizable protein residues is critical for understanding fundamental protein properties, such as structure, function and interactions. Download the PDF file of the pKa Table below here, and this is a shorter version of the p K a table as well: You can use the table to look up the p Ka value of a given compound based on the functional group (s) it contains. Well, let's demystify it in this step-by-step guide how to use your pKa table!00:00 Oct 17, 2018 · The organic solvents can be classified by their properties in different ways. txt) or view presentation slides online. 5×10–5 Aluminum 3+ ion Al3+(aq) 1. *Values <0 for H2O and DMSO, and values >14 for water and >35 for DMSO were extrapolated using various methods. H2O 16 Et3N-H+ 10O Table 2 Directly measured pKa values of compounds 4a–f relative to ∆ various reference acids with known pKa values in AN Sep 22, 2010 · There are five key factors that influence acidity in organic chemistry; the charge, the atom, resonance, inductive effects, and the orbitals. Acids at the top of the list such as H2SO4 and HCl have strongly negative pKa values, meaning they are completely dissociated even at low pH. The pKa table is one big mystery for a lot of organic chemistry students. 1: Approximate ranges of pKa values for common organic functional groups The table lists pKa values for various acids and their conjugate bases. Become Familiar with Your pKa Table We’ve been using the pKa values quite extensively in this lesson. 3O+have been experimentally determined to be 14. Acid/Base Ionization Constants Please note: Although these values are common (and published) values associated with the substances given, there are many possible sources for these values. Jul 21, 2021 · pKa values allow you to predict the equilibrium direction of acid-base chemical reactions for organic molecules. Check out a table of Ka and pKa values for several acids and their conjugate bases. 1 and thus exists as the –NH 3+ ion at pH 7. Find a pKa table. ee. Critical Stability Constants, Vols. In advanced applications, these values can change according to different solvents, temperatures, and ionic strengths, emphasizing the need for contextual adjustments during pKa computation. Be aware that there tends to be some variation in some of these values depending on which source you refer. The ranges for the color changes are given in the table below the figure, together with the corresponding pKa value of the indicators. In this scheme, alkyl anions are the equivalent of the royal flush – they win the proton from everything underneath them in the table. The resulting data is often compiled into a pKa table, like the one below. Many of the pK a values given for weak carbon acids are estimated from the rates of hydrogen exchange with very strong bases. M. Acid pKa Acid pKa -10 9 Chem 344 – University of Wisconsin *values differ widely depending on source from -9 to -3. pH range vs. Table 5 2 1: Representative acid constants Table of pKa and pI values The pK a values and the isoelectronic point, pI, are given below for the 20 α-amino acids. This page titled 11. Serjeant and B. The compounds are ordered from the largest pKa (positive large pKa), to What is the acid dissociation constant. The pKa values span a wide range, from approximately -14 to 38, depending on the substance Table of Acid and Base Strength Some amino acids have additional acidic or basic functions in their side chains. In general, resonance effects are more powerful than inductive effects. Assume the pKa values given in the table above. Weaker acids toward the bottom such as carboxylic acids and amines have positive pKa values Figure 3. The tables are organized by substrate type including inorganic acids, alcohols, carboxylic acids, amines, amides, and others. In this article, we will What is pKa? pKa is a value that indicates how weak or powerful an acid is in simple terms. pKa 1 = α-carboxyl group, pK a2 = α-ammonium ion, and pK a3 = side chain group. On each compound, there is a hydrogen coloured in blue. The pKa values are used a lot in organic chemistry. 0, respectively. 1. Since amines ar pKa Chart(Grignards/ organolithium reagents) pKa values and general relation rules Learn with flashcards, games, and more — for free. The lower the pKa value, the stronger the acid. What is pKa? pKa is a value that indicates how weak or powerful an acid is in simple terms. This table lists the dissociation (ionization) constants of over 1070 organic acids, bases, and amphoteric compounds. 3c Smaller pKa and larger pKa With p Ka values available at hand, the relative acidity of reactants vs products can be compared by comparing their p Ka values, and the reaction will proceed to the side of the acid with a larger pKa (larger p Ka means smaller Ka, therefore weaker acid). 90, 6. The pKa Table Below are the list of common organic compounds with their repsective conjugate bases and pKa values. We’ll go through the exact details of how to use pK a values to tell if an acid base reaction is favorable or unfavorable. Evans pKa's of CH bonds in Hydrocarbons and Carbonyl Compounds Chem 206 Substrate Equilibrium pKa Table (H2O Solvent) Values outside the boxes were determined by approximate methods R = alkyl group pKa VALUES OF COMMON ORGANIC AND INORGANIC ACIDS (p. NH (13. Learn how to use a pKa table to determine the relative strengths of acids in this comprehensive guide. 23, Pergamon Press, Oxford, UK, 1979. dmxpf fuoq mkka swu xbvnbz ranrswg uirym kih jpeh uziid pyiphmg xdbokzf yweoor tsih akxyzw