Question

What is the pH if 0.0256 g of Potassium Hydroxide are dissolved in enough water to make .212 liters of solution? (Hint: you are
solving for poH first and then finding pH)

Answer 1

pH= 11.332

Further explanation

KOH⇒K⁺+OH⁻

KOH(MW=56,1056 g/mol)

mol KOH :

$\tt \dfrac{0.0256}{56.1056}=4.56\times 10^{-4}$

molarity KOH :

$\tt \dfrac{4.56\times 10^{-4}}{0.212}=2.15\times 10^{-3}$

[OH⁻]=[KOH]=2.15 x 10⁻³

pOH=-log[OH⁻]

$\tt pOH=-log~2.15\times 10^{-3}\\\\pOH=3-log~2.15\\\\pOH=2.668$

pH+pOH=14

$\tt pH=14-2.668=\boxed{\bold{11.332}}$