Ka, or acid dissociation constant, is a measure of the strength of an acid in solution. It represents the extent to which an acid donates protons (H+) in water.
Acid strength refers to how easily an acid donates protons. Strong acids have high acid strengths and fully dissociate in solution.
A weak acid is one that only partially dissociates into ions when dissolved in water. The value of Ka for a weak acid will be small.
pH is a measure of the acidity or alkalinity (basicity) of a solution. It is determined by the concentration of H+ ions present.