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Stronger acids have a larger and a smaller logarithmic constant (= ) than weaker acids. The stronger an acid is, the more easily it loses a proton, H + {\displaystyle {\ce {H+}}} . Two key factors that contribute to the ease of deprotonation are the polarity of the H − A {\displaystyle {\ce {H-A}}} bond and the size of atom A, which ...
Nitric acid, with a pK value of around −1.7, behaves as a strong acid in aqueous solutions with a pH greater than 1. [23] At lower pH values it behaves as a weak acid. pK a values for strong acids have been estimated by theoretical means. [24] For example, the pK a value of aqueous HCl has been estimated as −9.3.
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 HCl solution. Any acid with a pK a less than about −2 is said to be a strong acid. Strong acids are said to be fully dissociated.
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 ...
The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase.The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (E pa = 1843 kJ/mol), [3] followed by the methanide anion (E pa = 1743 kJ/mol) and the hydride ion (E pa = 1675 kJ/mol), [4] making methane the weakest proton acid [5] in the gas phase, followed by dihydrogen.
When a strong acid is dissolved in water, it reacts with it to form hydronium ion (H 3 O +). [2] An example of this would be the following reaction, where "HA" is the strong acid: HA + H 2 O → A − + H 3 O + Any acid that is stronger than H 3 O + reacts with H 2 O to form H 3 O +. Therefore, no acid stronger than H 3 O + exists in H 2 O.
Commercially available superacids include trifluoromethanesulfonic acid (CF 3 SO 3 H), also known as triflic acid, and fluorosulfuric acid (HSO 3 F), both of which are about a thousand times stronger (i.e. have more negative H 0 values) than sulfuric acid. Most strong superacids are prepared by the combination of a strong Lewis acid and a ...
A base that has a large K b will ionize more completely and is thus a stronger base. As shown above, the pH of the solution, which depends on the H + concentration, increases with increasing OH − concentration; a greater OH − concentration means a smaller H + concentration, therefore a greater pH.