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Between the two buffer regions there is an end-point, or equivalence point, at about pH 3. This end-point is not sharp and is typical of a diprotic acid whose buffer regions overlap by a small amount: pK a2 − pK a1 is about three in this example. (If the difference in pK values were about two or less, the end-point would not be noticeable ...
In the case of multiple pK values they are designated by indices: pK 1, pK 2, pK 3 and so on. For amino acids, the p K 1 constant refers to its carboxyl (–COOH) group, p K 2 refers to its amino (–NH 2 ) group and the p K 3 is the p K value of its side chain .
Bjerrum plot of speciation for a hypothetical monoprotic acid: AH concentration as a function of the difference between pK and pH. Carbonic acid is the formal Brønsted–Lowry conjugate acid of the bicarbonate anion, stable in alkaline solution. The protonation constants have been measured to great precision, but depend on overall ionic ...
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 difference between successive pK a values is sufficiently large so that salts of either monohydrogen phosphate, HPO 2− 4 or dihydrogen phosphate, H 2 PO − 4, can be prepared from a solution of phosphoric acid by adjusting the pH to be mid-way between the respective pK a values.
The difference in size and volume is perhaps the most important distinction between the two types of salt. If you are measuring by volume—using teaspoon measurers, for example—you'll get a lot ...
Unrefined sea salt is minimally processed, retaining trace minerals that might lend color or flavor to the salt. (Refined sea salt, though, has been washed to remove minerals and contaminants, so ...
At pH 1 or lower, the phosphoric acid is practically undissociated. Around pH 4.7 (mid-way between the first two pK a values) the dihydrogen phosphate ion, [H 2 PO 4] −, is practically the only species present. Around pH 9.8 (mid-way between the second and third pK a values) the monohydrogen phosphate ion, [HPO 4] 2−, is the only species ...