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The Henderson–Hasselbalch equation relates the pH of a solution containing a mixture of the two components to the acid dissociation constant, K a of the acid, and the concentrations of the species in solution. [6] Simulated titration of an acidified solution of a weak acid (pK a = 4.7) with alkali
Therefore, the buffer regions will be centered at about pH 1.3 and pH 4.3. The buffer regions carry the information necessary to get the pK a values as the concentrations of acid and conjugate base change along a buffer region. Between the two buffer regions there is an end-point, or equivalence point, at about pH 3.
Species concentrations calculated with the program HySS for a 10 mM solution of citric acid. pK a1 = 3.13, pK a2 = 4.76, pK a3 = 6.40. A weak acid may be defined as an acid with pK a greater than about −2. An acid with pK a = −2 would be 99 % dissociated at pH 0, that is, in a 1 M
Phase behavior Triple point: 150 K (−123 °C), 0.00043 Pa Critical point: 514 K (241 °C), 63 bar Std enthalpy change of fusion, Δ fus H o +4.9 kJ/mol
The Hammett acidity function (H 0) is a measure of acidity that is used for very concentrated solutions of strong acids, including superacids.It was proposed by the physical organic chemist Louis Plack Hammett [1] [2] and is the best-known acidity function used to extend the measure of Brønsted–Lowry acidity beyond the dilute aqueous solutions for which the pH scale is useful.
The pH of a simple solution of an acid in water is determined by both and the acid concentration. For weak acid solutions, it depends on the degree of dissociation, which may be determined by an equilibrium calculation. For concentrated solutions of acids, especially strong acids for which pH < 0, the value is a better measure of acidity than ...
In strongly basic solutions, phenolphthalein is converted to its In(OH) 3− form, and its pink color undergoes a rather slow fading reaction [6] and becomes completely colorless when pH is greater than 13. The pK a values of phenolphthalein were found to be 9.05, 9.50 and 12 while those of phenolsulfonphthalein are 1.2 and 7.70.
The pH-dependence of the activity displayed by enzymes and the pH-dependence of protein stability, for example, are properties that are determined by the pK a values of amino acid side chains. The p K a values of an amino acid side chain in solution is typically inferred from the p K a values of model compounds (compounds that are similar to ...