What is the pH of a bleach solution that has a [OH−]=3.2×10−3 M? pH=

Answer 1

Hi Josh,

There are two ways we can find pH:

First method:

Since we have [OH^-] we can use the pOH formula first

pOH = -log[OH^-]

pOH = -log(3.2 • 10^-3)

pOH = 2.49

Now we use this formula to find pH by plugging in the pOH we just found:

pH + pOH = 14

pH + 2.49 = 14

pH = 11.51

Second Method:

Use the K_w formula to find [H⁺] then use pH formula

K_w = [H⁺][OH^-]

1.0 • 10^-14 = [H⁺][OH^-]

*Let’s plug in [OH^-] to the formula

1.0 • 10^-14 = [H⁺][3.2•10^-3]

*Divide to isolate [H⁺]

[H⁺] = 3.13 • 10^-12

Now let’s plug the [H⁺] we just found into the pH formula

pH = -log[H⁺]

pH = -log(3.13 • 10^-12)

pH = 11.5

Answer: pH = 11.5

Hope this helps :)

Answer 2

hydroxide concentration x hydrogen ion concentration = 10^-14

pH = -log([H⁺])

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