Achieve Wk2 #3

[Leslie Hernandez 1E]

Muscles produce lactic acid, CH3CH(OH)COOH(aq), during exercise. Calculate the percent ionization (deprotonation), pH, and pOH
of a 0.1097 M solution of lactic acid. The acid‑dissociation (or ionization) constant, Ka, of this acid is 8.40×10−4.

percent ionization=

pH=

pOH=

I tried solving for the ionization first however I didn't get the right answer.

Here are my steps.

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

8.4x10ˆ-4 = Xˆ2/0.1097-X

0 = 0.000092 - 0.00084x - xˆ2

Then I used the quadratic formula to get a really small number. Then I divided it with the initial concentration and multiplied it by 100 to get the percent. I ended up getting 6.8 percent which isn't correct.

[Megan Efhan 3A]

If you multiply your quadratic equation by -1 it might make it easier to solve. I think something went wrong when you solved your quadratic equation - I solved it and got an x value of .00918. I would just double check your work.

[Xinye Yu 2A]

Maybe you did your math wrong? I got x=0.009189. Divide that by the initial and you should get 0.083765 which is around 8.4%