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Grotthuss mechanism: how protons are transferred between hydronium ions and water molecules, accounting for the exceptionally high ionic mobility of the proton (animation). Hammett acidity function: a measure of acidity that is used for very concentrated solutions of strong acids, including superacids. Ion transport number
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.
The bicarbonate ion (hydrogencarbonate ion) is an anion with the empirical formula HCO − 3 and a molecular mass of 61.01 daltons; it consists of one central carbon atom surrounded by three oxygen atoms in a trigonal planar arrangement, with a hydrogen atom attached to one of the oxygens.
In chemistry a donor number (DN) is a quantitative measure of Lewis basicity.A donor number is defined as the negative enthalpy value for the 1:1 adduct formation between a Lewis base and the standard Lewis acid SbCl 5 (antimony pentachloride), in dilute solution in the noncoordinating solvent 1,2-dichloroethane with a zero DN.
The precise measurement of pH is presented in International Standard ISO 31-8 as follows: [15] A galvanic cell is set up to measure the electromotive force (e.m.f.) between a reference electrode and an electrode sensitive to the hydrogen ion activity when they are both immersed in the same aqueous solution.
The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase.The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (E pa = 1843 kJ/mol), [3] followed by the methanide anion (E pa = 1743 kJ/mol) and the hydride ion (E pa = 1675 kJ/mol), [4] making methane the weakest proton acid [5] in the gas phase, followed by dihydrogen.
where 2.60 is the correction for the oxidative dimerization of water, obtained from a least-squares correlation of data in Edwards’ first paper on the subject. [1] α and β are then parameters unique to specific nucleophiles that relate the sensitivity of the substrate to the basicity and polarizability factors. [6]
Physiologically normal intracellular pH is most commonly between 7.0 and 7.4, though there is variability between tissues (e.g., mammalian skeletal muscle tends to have a pH i of 6.8–7.1). [4] [5] There is also pH variation across different organelles, which can span from around 4.5 to 8.0. [6] [7] pH i can be measured in a number of ...