[munoz_m1]

The question is:
Calculate the pH of each of the following solutions:
(1) A sample of seawater that has an OH- concentration of 1.58 x 10-6 M

So I came up with: pH=14 for the first question but I can't figure out the second part of the question which is:

(2) A sample of acid rain that has an H3O+ concentration of 6.0 x 10-5 M.

[I follow example questions in my text book to help guide me through practice problems, but in my book I can't figure the second question because the book uses OH problems.]

[Arkcon]

Does you answer to number one really seem plausible to you?  You think seawater is stronger than oven cleaner?  Remind me not to go swimming where you go.

OK, let's see the formula you're using, you may have gotten it backwards.

[flightman233]

I would definitely go back and recheck your answer for part A.

when you take the -log of [OH-] you get pOH.

pH + pOH = 14.  So 14 - pOH gives you pH.  You should have come up with an approximate value of 5.80 for pOH.  Subtracting from 14 gives you a pH of about 8.2.

Now, the next problem is relatively straight forward just take the -log of [H+].

So -log[6.0X10-5] = 4.22 = pH

hope that helps.