Why does ka get smaller for Polyprotic acids?
For polyprotic acids, the first Ka is always the largest, followed by the second, etc.; this indicates that the protons become successively less acidic as they are lost.
Should I use Ka1 or Ka2?
As such, unlike most other acids with multiple Hydrogens, sulfuric acid has a high Ka2 which makes it strong. Overall, acids that dissociative multiple times are weak and we can use Ka1 as an approximation because Ka2 is a considerably smaller number.
How do you find Ka2?
Ka2 = = = 6.3 x 10-8 = y (assume y << 0.19) y = 6.3 x 10-8 (very small – assumption definitely okay !!) (2) [H+] from second dissociation is negligible!
What is the relationship between KA and KB values?
The Ka is the acid dissociation constant. The larger the value of Kb, the stronger the base, and the larger the value of Ka, the stronger the acid. By multiplying Ka by Kb, you receive the Kw, or the dissociation constant for water, which is 1.0 x 10^-14.
What is Ka Chem?
The acid dissociation constant (Ka) is used to distinguish strong acids from weak acids. Strong acids have exceptionally high Ka values. The Ka value is found by looking at the equilibrium constant for the dissociation of the acid. The higher the Ka, the more the acid dissociates.
What is Ka of acetic acid?
| Ka of Weak Acids | ||
|---|---|---|
| acetic | HC2H3O2 | 4.7 |
| ascorbic (I) | H2C6H6O6 | 4.1 |
| ascorbic (II) | HC6H6O6- | 11.8 |
| benzoic | HC7H5O2 | 4.2 |
How do you know which Ka value to use?
The Ka value is found by looking at the equilibrium constant for the dissociation of the acid. The higher the Ka, the more the acid dissociates. Thus, strong acids must dissociate more in water. In contrast, a weak acid is less likely to ionize and release a hydrogen ion, thus resulting in a less acidic solution.
What do KA and KB values mean?
For an aqueous solution of a weak acid, the dissociation constant is called the acid ionization constant (Ka). Similarly, the equilibrium constant for the reaction of a weak base with water is the base ionization constant (Kb).
What is the relationship between KA and KB with KW Brainly?
What is the relationship between Ka and Kb with Kw? The sum of Ka and Kb equals the auto-dissociation constant for water. The product of Ka and Kb equals the auto-dissociation constant for water.
What is Ka value of an acid?
Does Ka change with concentration?
The concentrations in the expression of Ka are the equilibrium concentration, they change however, their ratio remains constant, and therefore, the name of constant Ka . The ONLY factor that affect Ka is temperature, and therefore there is no influence of concentration change on the value of Ka .
How to determine the Ka of a triprotic acid?
For a triprotic acid, the other two equivalence points should correspond to 1/3 and 2/3 of the volume of the base required to reach the final one and thus one can still determine the Ka values. Note, however, I did say the vast majority of the time.
How many equivalence points does a polyprotic acid have?
Polyprotic acids display as many equivalence points in titration curves as the number of acidic protons they have; for instance, a diprotic acid would have two equivalence points, while a triprotic acid would have three equivalence points.
How are the titrations of a weak polyprotic acid related?
So, in essence, titrations of a weak polyprotic acid with a strong mono protic base are a combination of a number of titrations depending on the number of acidic protons on the polyprotic acid. The overall reaction is the sum of the two titration’s
Which is a triprotic base of a polyprotic acid?
(aq) (ii) The conjugate bases are polyprotic bases, i.e., PO 4 3- is a triprotic base – it can pick up 3 H+. 18-2 Table 18.5 Successive K avalues for Some Polyprotic Acids at 25°C 18-3