pH and pOH

Rucete ✏ Chemistry In a Nutshell

1. What Is pH?

• pH measures the hydrogen ion concentration [H⁺] in a solution.
• Formula: pH = -log[H⁺]

2. What Is pOH?

• pOH measures the hydroxide ion concentration [OH⁻] in a solution.
• Formula: pOH = -log[OH⁻]

3. Relationship Between pH and pOH

• pH and pOH are related through water’s ion product constant (Kw).
• pH + pOH = 14
• [H⁺][OH⁻] = 1.0 × 10⁻¹⁴

4. Interconverting [H⁺], [OH⁻], pH, and pOH

• If you know one value (e.g., pH), you can calculate the others using:
  • pH = -log[H⁺]
  • pOH = -log[OH⁻]
  • pH + pOH = 14

5. Acidic and Basic Ranges

• Acidic solution: pH < 7
• Neutral solution: pH = 7
• Basic solution: pH > 7

In a nutshell

Low pH = More H⁺ = Acidic!

• pH down → [H⁺] up
• pH up → [OH⁻] up
• pH + pOH = 14