What is the concentration of $OH^-$ ions in a solution ... – Chemistry

Chemistrymedium · Past Paper

What is the concentration of $OH^-$ ions in a solution with pH 9?

A$10^{-9}$ mol/L

B$10^{-5}$ mol/L

C$10^9$ mol/L

D$10^5$ mol/L

✓ Correct Answer: B — $10^{-5}$ mol/L

At 25°C, pH + pOH = 14. If pH=9, pOH=5, so [OH-] = $10^{-5}$.

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