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# Calculate pH and % Ionization from Ka

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I'm given the Ka and concentration to calculate the pH then find % ionization. I utilized an ice table and made the assumption that x << the # i'm working with, however, when I check the assumption... its not < 5% snd plugged my #'s into the quadratic formula and both #'s check... when one # is usually eliminated and I'm left with the correct x value. I've checked my calcultions numerous times and am simply lost. I'm working with trichloroacetic acid and am assuming it is a weak acid and does not completely dissociate. Is this where I'm going wrong?

https://brainmass.com/chemistry/acids-and-bases/calculate-ph-ionization-ka-257485

#### Solution Preview

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The equilibrium expression can be written as:

You know the Ka and the concentration of HA. Because the Ka is only 0.23, you can't neglect the x term ...

#### Solution Summary

This solution explains how to calculate the pH and the percent ionization of trifluoroacetic acid based on an initial concentration and Ka.

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