Unit 7: Equilibrium And Acids

Section 7: More Misc Facts About Acids And Bases

* Water Plays A Role
* pH Scale
* Conclusion

Water Plays A Role

I hope you have noticed that in most of the reactions tht we have talked
about, water as the substance thtt breaks up the acid and also, many of the
acids and ions are in aqueous states. And, this is the case for many of the
acid-base reactions, and this is good because it helps us make a few
generalities.

First, the dissociatin constant for water (Kw) is equal to:

Kw = [H3O+] [OH-] = [H+] [OH-]

also we know that in a neutral solution, we know that the H+ concentration
is equal to 1.0 x 10-7 and the OH- concentration is equal to 1.0 x 10-7, so
by doing some math, we can solve for Kw.

Kw = 1.0 x 10-14

This constant can be applied to all reactions involving aqueous solutions,
and it will become the basis for the pH scale.

pH Scale

The pH scale is an easy way to classify how strong an acid or a base is. The
pH scale is a scale from 0 to 14. On the scale, 0 is the strongest acid, 14
is the strongest base, and a neutral solution is located at 7. So if you
know that substance had a pH of 6, you would know tha it was a weak acid. If
you were given a substance with a pH of 13, you would know that it was a
strong base. Also, if you were given the H+ concentration of an acid or base
you can use the below formula to find the pH for that substance.

pH = - log [H+]

 

If you were given the OH- concentration of an acid or base, you would have
to use the below equation.

pH = 14 - (- log [H+])

Conclusion

This is about as much informatin as I can give at this time without going
into the math behind acids and bases. From here on, you have gotten into the
middle of college level chemistry, so take pride in that!