Question

Calculate the hydroxide ion concentration of a solution with pH = 8.25.

Answer 1

The pH of a solution tells you the concentration of the H+ ions in solution. However, if we know the pH, we can calculate the pOH and from that, the concentration of the OH- ions in solution.

pH + pOH = 14
if pH = 8.25, pOH = 14-8.25 = 5.75

Just like pH = -log([H+]),
pOH = -log([OH-])

If pOH = 5.75, that means that -log([OH-]) = 5.75, which mean that 10^-5.75 much give us the concentration of OH- ions.

10^-5.75 = 1.778 E-6
So we know that the concentration of the OH- ions in the solution with a pH of 8.25 is 1.778 E-6 Molar.

[OH-] = 1.778 E-6 M

Answer 2

I agree with all of this.

Answer 3

Thank you !!! :)