P

pH

pH = -log₁₀[H⁺]
Quick Reference
Formula / NotationpH = -log₁₀[H⁺]
Also Known AsHydrogen ion potential, Power of hydrogen

What is pH?

A measure of the hydrogen ion concentration in a solution, defined as pH = -log₁₀[H⁺]. In pure water at 25°C, [H⁺] = 10⁻⁷ M and pH = 7. Values below 7 are acidic; values above 7 are basic. The pH scale is central to understanding acid-base chemistry in aqueous solutions.

Formula & Notation

pH = -log₁₀[H⁺]

Other Names / Synonyms: Hydrogen ion potential, Power of hydrogen

Properties & Characteristics

Logarithmic scale where each unit = 10× concentration change. Acidic: 0–6.9. Neutral: 7. Basic/Alkaline: 7.1–14. Kw = [H+][OH-] = 1.0 × 10⁻¹⁴ at 25°C. Strong acids: HCl (pH near 0). Body fluids: blood pH 7.4, stomach pH 1–2, urine pH 4.6–8.

Uses & Applications

Clinical diagnostics, fermentation control, enzyme activity optimization, food safety testing, cosmetics formulation, environmental science, acid-base titration endpoint detection.

Safety Information

Handle pH-modifying chemicals with full PPE. Strong acids and bases are corrosive to skin, eyes, and respiratory tract. Neutralize before disposal.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term pH
Formula pH = -log₁₀[H⁺]
Synonyms Hydrogen ion potential, Power of hydrogen

Frequently Asked Questions

A measure of the hydrogen ion concentration in a solution, defined as pH = -log₁₀[H⁺]. In pure water at 25°C, [H⁺] = 10⁻⁷ M and pH = 7. Values below 7 are acidic; values above 7 are basic. The pH scale is central to understanding acid-base chemistry in aqueous solutions.

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