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The constant for dissociation of the first proton may be denoted as K a1 and the constants for dissociation of successive protons as K a2, etc. Phosphoric acid, H 3 PO 4, is an example of a polyprotic acid as it can lose three protons.
Strong acids, such as sulfuric or phosphoric acid, have large dissociation constants; weak acids, such as acetic acid, have small dissociation constants. The symbol K a, used for the acid dissociation constant, can lead to confusion with the association constant, and it may be necessary to see the reaction or the equilibrium expression to know ...
K a is variously named a dissociation constant, [3] an acid ionization constant, [2]: 668 an acidity constant [1] or an ionization constant. [2]: 708 It serves as an indicator of the acid strength: stronger acids have a higher K a value (and a lower pK a value).
3 (i.e. the first acid dissociation constant for carbonic acid), K 2 is the equilibrium constant for the reaction HCO − 3 ⇌ H + + CO 2− 3 (i.e. the second acid dissociation constant for carbonic acid), and DIC is the (unchanging) total concentration of dissolved inorganic carbon in the system, i.e. [CO 2] + [HCO − 3] + [CO 2− 3].
Most of the carbonic acid then dissociates to bicarbonate and hydrogen ions. The bicarbonate buffer system is an acid-base homeostatic mechanism involving the balance of carbonic acid (H 2 CO 3), bicarbonate ion (HCO − 3), and carbon dioxide (CO 2) in order to maintain pH in the blood and duodenum, among other tissues, to support proper ...
The strength of a weak acid is quantified by its acid dissociation constant, value. The strength of a weak organic acid may depend on substituent effects. 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.
The term superacid was originally coined by James Bryant Conant in 1927 to describe acids that were stronger than conventional mineral acids. [1] This definition was refined by Ronald Gillespie in 1971, as any acid with an H 0 value lower than that of 100% sulfuric acid (−11.93). [3]
Polyprotic acids are acids that can lose more than one proton. The constant for dissociation of the first proton may be denoted as K a1, and the constants for dissociation of successive protons as K a2, etc. Citric acid is an example of a polyprotic acid H 3 A, as it can lose three protons.