Calculate the [OH-] given [H3O+]=6.5×10−4M.

Answer 1

To calculate concentration of [OH^-] you will need the formula

K_w=[H₃O⁺][OH^-]

Where K_w= 1·10^-14

So since [H₃O⁺] = 6.5·10^-4 we can just plug in the known values and solve for [OH^-]

1·10^-14 = [6.5·10^-4][OH^-]

Then divide both sides by [6.5·10^-4] to get the [OH^-] alone

[1·10^-14]/[6.5·10^-4] = [6.5·10^-4][OH^-]/[6.5·10^-4]

When divided out the left side equals 1.5·10^-11

And the right side both the [6.5·10^-4] cancel out to leave the [OH^-] by itself

So therefore the answer is: 1.5·10^-11 = [OH^-]