What is the OH- concentration in 0.150 M HClO4?
Perchloric acid (HClO4) is a strong acid and dissociates completely in water to give a proton (H+) and perchlorate ion (ClO4-).
Thus, the hydrogen ion concentration in the given solution is:
[H+] = [HClO4] = 0.15 M
Since in a given solution, the product of concentrations of hydrogen ion and hydroxide ion is always equal to 10^-14, we can use this to calculate the concentration of hydroxide ions in the solution.
In other words, [H+] x [OH-] = 10^-14
or, [OH-] = 10^-14 / [H+] = 10^-14 / 0.15 = 6.67 x 10^-14 M
We can also use these numbers to calculate pH and pOH of the solution.
pH = - log [H+] = - log (0.15) = 0.824
and pOH = 14 - pH = 14 - 0.824 = 13.176
Hope this helps.