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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 ...
Alternatively, various numerical formulas have been proposed including pK a = 8 − 5m (known as Bell's rule), [29] [47] pK a = 7 − 5m, [30] [48] or pK a = 9 − 7m. [29] The dependence on m correlates with the oxidation state of the central atom, X: the higher the oxidation state the stronger the oxyacid.
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 ...
In chemistry and biochemistry, the Henderson–Hasselbalch equation = + ([] []) relates the pH of a chemical solution of a weak acid to the numerical value of the acid dissociation constant, K a, of acid and the ratio of the concentrations, [] [] of the acid and its conjugate base in an equilibrium.
The Joback method, often named Joback–Reid method, predicts eleven important and commonly used pure component thermodynamic properties from molecular structure only. It is named after Kevin G. Joback in 1984 [1] and developed it further with Robert C. Reid. [2] The Joback method is an extension of the Lydersen method [3] and uses very similar groups, formulas, and parameters for the three ...
FDPB-based methods calculate the change in the pK a value of an amino acid side chain when that side chain is moved from a hypothetical fully solvated state to its position in the protein. To perform such a calculation, one needs theoretical methods that can calculate the effect of the protein interior on a p K a value, and knowledge of the pKa ...
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 subscript r {\displaystyle r} means "reaction" and the superscript ⊖ {\displaystyle \ominus } means "standard".
The buffering region is dependent upon the pKa, and is typically +/- 1.0 pH units of the pKa. 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 ...