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For example, acetic acid is a weak acid which has a = 1.75 x 10 −5. Its conjugate base is the acetate ion with K b = 10 −14 /K a = 5.7 x 10 −10 (from the relationship K a × K b = 10 −14), which certainly does not correspond to a strong base. The conjugate of a weak acid is often a weak base and vice versa.
A weak acid cannot always be neutralized by a weak base, and vice versa. However, for the neutralization of benzoic acid (K a,A = 6.5 × 10 −5) with ammonia (K a,B = 5.6 × 10 −10 for ammonium), K = 1.2 × 10 5 >> 1, and more than 99% of the benzoic acid is converted to benzoate.
Acid-neutralizing capacity or ANC in short is a measure for the overall buffering capacity against acidification of a solution, e.g. surface water or soil water.. ANC is defined as the difference between cations of strong bases and anions of strong acids (see below), or dynamically as the amount of acid needed to change the pH value from the sample's value to a chosen different value. [1]
For example, aqueous perchloric acid (HClO 4), aqueous hydrochloric acid (HCl) and aqueous nitric acid (HNO 3) are all completely ionized, and are all equally strong acids. [3] Similarly, when ammonia is the solvent, the strongest acid is ammonium (NH 4 +), thus HCl and a super acid exert the same acidifying effect. The same argument applies to ...
In water, measurable pK a values range from about −2 for a strong acid to about 12 for a very weak acid (or strong base). A buffer solution of a desired pH can be prepared as a mixture of a weak acid and its conjugate base. In practice, the mixture can be created by dissolving the acid in water, and adding the requisite amount of strong acid ...
Note that when an acid neutralizes a base, the pH may or may not be neutral (pH = 7). The pH depends on the strengths of the acid and base. In the case of a weak acid and strong base titration, the pH is greater than 7 at the equivalence point. Thus pH can be calculated using the following formula: [1]
A weak base will have a higher H + concentration than a stronger base because it is less completely protonated than a stronger base and, therefore, more hydrogen ions remain in its solution. Given its greater H + concentration, the formula yields a lower pH value for the weak base.
The essence of Brønsted–Lowry theory is that an acid is only such in relation to a base, and vice versa. Water is amphoteric as it can act as an acid or as a base. In the image shown at the right one molecule of H 2 O acts as a base and gains H + to become H 3 O + while the other acts as an acid and loses H + to become OH −.