Question

10. Some of the acids listed in Question 7 have different masses, but the same K. How is this possible? Explain.

Answer 1

The acids sodium dihydrogen phosphate and sodium dihydrogen phosphate monohydrate both have the same Ka. Likewise in the given list all acids and their mohohydrates have the same Ka.

Acid dissociation constant Ka is the ratio of concentration of products to that of the concentration of the reactants after the ionization of the acid in the aqueous medium. The monohydrate of an acid contains only one water molecule excess to that of the acid and this water molecule combines with the water molecules those from the aqueous medium and the ionization will be same in water for both acid and its monohydrate. As the extent of ionization is same, these have the same acid dissociation constant values.