To find the pH from the [OH-] concentration of 5.9x10^-1 M, calculate the [H3O+] by dividing the ionic product of water by the [OH-] concentration, and then use the negative logarithm to find the pH.
To calculate the pH if the concentration of hydroxide ions ([OH-]) is 5.9x10-1 M, you first need to use the relation between the concentration of hydroxide ions and hydronium ions ([H3O+]) which is given by the ionic product of water (Kw).
The relation is Kw = [H3O+][OH-], and it's equal to 1x10-14 at 25°C.
[H3O+] = 1x10-14 / [OH-] = 1x10-14 / 5.9x10-1 = 1.69x10-14.
Then, we calculate the pH using the formula pH = -log[H3O+], which gives us pH = -log(1.69x10-14).
Finally, we calculate this value to get the pH.