=( given the hydrogen ion conc [H+] for each solution,find the pH and the hydroxide ion concentration [OH-]?

Question

Question: [H+] = 1.9x10^-6

pls help out, i have a few of the similar question, but no idea how to work it out. pls show me the wrking out. THX HEAPS

Answer 1

In 25 deg C water, Kwa= 1x10-14 = [H+][OH-].
So the OH- = 10x10-15 / 1.9x10-6 = 5.1 x 10-9.
To find pH, you take log 1/[H+]. To get 1/[H+], you do something similar to what you did with OH],
10 x 10-1 / 1.9 x 10-6 = 5.1 x 10^5. Now you take the log of this and get about 5.71.