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pKa values for acetic, chloroacetic, dichloroacetic and trichloroacetic acids. Inductive effects and mesomeric effects affect the p K a values. A simple example is provided by the effect of replacing the hydrogen atoms in acetic acid by the more electronegative chlorine atom.
The following table presents pK a values at 20 °C. Values change by about 0.01 per degree of temperature. [1] [3] Good's original 1966 paper had two older buffers (marked with italics) for comparison. In 1972 Good published a second list with three more buffers, and five more were added in 1980.
See Amino acid for the pK a values of all amino acid side chains inferred in such a way. There are also numerous experimental studies that have yielded such values, for example by use of NMR spectroscopy. The table below lists the model pK a values that are often used in a protein pK a calculation, and contains a third column based on protein ...
In chemistry, biochemistry, and pharmacology, a dissociation constant (K D) is a specific type of equilibrium constant that measures the propensity of a larger object to separate (dissociate) reversibly into smaller components, as when a complex falls apart into its component molecules, or when a salt splits up into its component ions.
It is also relatively acidic, with a pKa of 9.3, comparable to that for phenol. [1] It is classified as a hard Lewis acid and its acceptor properties are discussed in the ECW model. [3] [4] Hexafluoro-propan-2-ol is a speciality solvent for organic synthesis, particularly for reactions involving oxidations and strong electrophiles.
The pKa of KHP is 5.4, so its pH buffering range would be 4.4 to 6.4; however, due to the presence of the second acidic group that bears the potassium ion, the first pKa also contributes to the buffering range well below pH 4.0, which is why KHP is a good choice for use as a reference standard for pH 4.00. [8] [9]
With aqueous pK a values of around 16–19, alcohols are, in general, slightly weaker acids than water. With strong bases such as sodium hydride or sodium they form salts [a] called alkoxides, with the general formula RO − M + (where R is an alkyl and M is a metal). R−OH + NaH → R−O − Na + + H 2 2 R−OH + 2 Na → 2 R−O − Na + + H 2
Acid strength is the tendency of an acid, symbolised by the chemical formula, to dissociate into a proton, +, and an anion, .The dissociation or ionization of a strong acid in solution is effectively complete, except in its most concentrated solutions.