Question

How does ${{K}_{a}}$ relate to acid strength?

Answer 1

Hint ${{K}_{a}}$ is called an acid dissociation constant. By using ${{K}_{a}}$ value we can find the strength of the acid. Acid in water going to ionize (dissociates) and forms respective ions. The dissociation capacity of the acids is going to measure using ${{K}_{a}}$ .

Complete step by step answer:
- In the question it is asked how ${{K}_{a}}$ value relates to the strength of the acid.
- The strength of the acid in a solution and ${{K}_{a}}$ value are directly proportional to each other.
- Means if the acid is too strong it dissociates completely in the water then the value of ${{K}_{a}}$ is very high and the respective acid is a weak base.
- For example coming to the ${{K}_{a}}$ value of acetic acid and it is $1.8\times {{10}^{-5}}$ in water.
- Means the $p{{K}_{a}}$ value of acetic acid is 4.76 and it is very less than acetic acid is a weak acid.
- Therefore by using the ${{K}_{a}}$ value we can find whether the given acid is strong or weak.
- ${{K}_{a}}$ is used to measure quantitatively the strength of the acid in the solution.
- By using ${{K}_{a}}$ one can easily identify which is strong acid and which not a strong acid is.
- In chemistry the extent of dissociation of an acid is going to measure using ${{K}_{a}}$ value.

Note: ${{K}_{a}}$ value does not determine the acid strength accurately. ${{K}_{a}}$ will determine the acid strength relative to the solvent. The higher the ${{K}_{a}}$ value of acid then the acid dissociates higher in that particular solvent.