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## Homework Statement

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. Homework Equations**

pH = -log[H+]

Ka = [H+][A-] / [HA]

pKa = -logKa

## The Attempt at a Solution

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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]?