Question

Calculate the pH given [OH-] = 2.0 x 10^-7

Answer 1

The pH is 7.302

Step-by-step explanation

Given that

`\text{ \lbrack OH}^-\text{ \rbrack }=\text{ 2.0 }*\text{ 10}^(-7)`

Follow the steps below to find the the pH

Step 1; Write the formula for calculating pOH

`\text{ pOH = -log \lbrack OH}^-\text{ \rbrack}`

Step 2; Substitute the value of [OH^-] = 2.0 x 10 ^-7

`\begin{gathered} \text{ pOH = -log \lbrack 2.0 }*\text{ 10}^{-7\text{ }}\text{ \rbrack} \\ \text{ pOH = 6.698} \end{gathered}`

Recall, that pH + pOH = 14

Hence, we can find pH

`\begin{gathered} \text{ pH + pOH = 14} \\ \text{ pH + 6.698 = 14} \\ \text{ pH = 14 - 6.698} \\ \text{ pH = 7.302} \end{gathered}`

Therefore, the pH is 7.302