1. The problem statement, all variables and given/known data The dissociation constant Ka for the acid-base reaction HA-->(H+)+(A-) is given by Ka = products / reactants; but instead of listing Ka, people generally list pKa = -logKa (where log indicates the 10-base logarithm). Similarly, instead of using [H+], people generally use pH = -log[H+] (equation 1) b.) Let (theta) be the fraction of acid molecules that is protonated; so clearly, (theta) is a number between 0 and 1. Express (theta) as a function of [H+] and Ka; fully simplify your answer 2. Relevant equations pH = -log[H+] Ka = [H+][A-] / [HA] pKa = -logKa 3. The attempt at a solution Pretty stuck on what I'm suppose to do. From looking at this and some titration graphs it seems that theta will be the 'Equivalents of H+ added'. It says let theta be the fraction of acid molecules that is protonated, so does that just mean (Ka = [theta][A-]/[HA])? And doing this as a function of [H+] = (theta) so then pH = -log[theta]?