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Acid dissociation constants are also essential in aquatic chemistry and chemical oceanography, where the acidity of water plays a fundamental role. In living organisms, acid–base homeostasis and enzyme kinetics are dependent on the pK a values of the many acids and bases present in
In physical chemistry, the Arrhenius equation is a formula for the temperature dependence of reaction rates.The equation was proposed by Svante Arrhenius in 1889, based on the work of Dutch chemist Jacobus Henricus van 't Hoff who had noted in 1884 that the Van 't Hoff equation for the temperature dependence of equilibrium constants suggests such a formula for the rates of both forward and ...
The Van 't Hoff equation relates the change in the equilibrium constant, K eq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, Δ r H ⊖, for the process.
The pK a 0 is weakly dependent on temperature. Phillips et al. reported ∆H 0 at 25 °C of 760 cal/mol (3180 J/mol) and a linear dependence of p K a 0 on 1/ T ( Van 't Hoff equation ). The positive ∆H 0 results in an increase in K a , and thus a decrease in p K a 0 with rising temperature, the change in pKa 0 being 166 × the change in (1/ T ...
The pH-dependent effects cannot be added in the same straightforward way and have to be accounted for using Boltzmann summation, Tanford–Roxby iterations or other methods. The interplay of the intrinsic p K a values of a system with the electrostatic interaction energies between titratable groups can produce quite spectacular effects such as ...
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 strength of an inorganic acid is dependent on the oxidation state for the atom to which the proton may be attached. Acid strength is solvent-dependent. Acid strength is solvent-dependent. For example, hydrogen chloride is a strong acid in aqueous solution, but is a weak acid when dissolved in glacial acetic acid .
Pressure dependence of the water ionization constant at 25 °C. In general, ionization in aqueous solutions tends to increase with increasing pressure. In a condensed phase, the pressure dependence of the equilibrium constant is associated with the reaction volume. [18] For reaction: α A + β B ⇌ σ S + τ T. the reaction volume is: