P

Parachor

[P] = M(γ)^(1/4) / (ρ_L - ρ_V)
Quick Reference
Formula / Notation[P] = M(γ)^(1/4) / (ρ_L - ρ_V)
Also Known AsSugden parachor, molecular parachor, parachor value

What is Parachor?

The parachor is a physico-chemical quantity that relates the surface tension of a liquid to its density, introduced by Sugden (1924). It is approximately constant and additive for different parts of a molecule, making it useful for predicting molecular structure. The parachor [P] = M × (γ)^(1/4) / (ρ_L − ρ_V), where M = molecular weight, γ = surface tension, ρ_L = liquid density, ρ_V = vapor density.

Formula & Notation

[P] = M(γ)^(1/4) / (ρ_L - ρ_V)

Other Names / Synonyms: Sugden parachor, molecular parachor, parachor value

Properties & Characteristics

Formula: [P] = M × γ^(1/4) / (ρ_L − ρ_V). Approximately additive: [P]_molecule ≈ Σ[P]_atoms + Σ[P]_bonds. Units: cm³ g^(1/4) s^(−1/2) mol^(−1). Useful for estimating molecular structure and surface tension. Temperature independent for liquids well below critical point.

Uses & Applications

Estimating surface tension of organic liquids. Predicting molecular structure from physical data. Chemical structure elucidation (historical). Lubricant and surfactant research. Quality control of organic compounds.

Safety Information

Calculation method — no direct safety concerns.

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

Key Facts

Term Parachor
Formula [P] = M(γ)^(1/4) / (ρ_L - ρ_V)
Synonyms Sugden parachor, molecular parachor, parachor value

Frequently Asked Questions

The parachor is a physico-chemical quantity that relates the surface tension of a liquid to its density, introduced by Sugden (1924). It is approximately constant and additive for different parts of a molecule, making it useful for predicting molecular structure. The parachor [P] = M × (γ)^(1/4) / (ρ_L − ρ_V), where M = molecular weight, γ = surface tension, ρ_L = liquid density, ρ_V = vapor density.

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