# Question ca771

May 24, 2017

pH = 11.87

#### Explanation:

We know if we have a given $\left[O {H}^{-}\right]$, then we can find $\text{pOH}$which is just the $\text{-log of the} \left[O {H}^{-}\right] .$

Find $\text{pOH}$

• $- \log \left[O {H}^{-}\right] \to - \log \left[7.5 \cdot {10}^{-} 3 M\right] \to 2.13$

$\textcolor{w h i t e}{a a a}$

We also know from the relationship that

color(white)(aaaaaa)color(green)("pH+pOH = 14 at "25^@"Celsius"#

so from the $\text{pOH}$ we can find the $\text{pH}$.

$\textcolor{w h i t e}{a a a}$

Find $\text{pH}$ from $\text{pOH}$

• $\text{pH+pOH = 14}$

• $\text{pH =14-2.13}$

• $\text{pH = 11.87}$