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Boiling & Freezing Point Calculator

GPSA Ch. 1

Boiling & Freezing Point Calculator
Determines boiling points and freezing points for pure hydrocarbon components and mixtures. Calculates pressure-adjusted boiling points via the Clausius-Clapeyron equation, and bubble/dew point temperatures for multi-component mixtures using Raoult's Law per GPSA Ch. 1. Read Fundamentals →
GPSA Ch. 1 GPA 2145
Calculation Mode:
Single Component: Look up boiling point, freezing point, and critical properties for a pure component at a specified pressure.

Pure Component

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Normal Boiling Points of Common Components

ComponentBP (°F)FP (°F)Tc (°F)
Methane-258.7-296.5-116.7
Ethane-127.5-297.090.1
Propane-43.7-305.8206.2
n-Butane31.1-217.0305.7
n-Pentane96.9-201.5385.7
n-Hexane155.7-139.6453.7
Water212.032.0705.4
CO₂-109.3-69.987.9
H₂S-76.5-121.9212.7

Engineering Basis

Clausius-Clapeyron Equation:

ln(P₂/P₁) = (ΔHvap/R) × (1/T₁ − 1/T₂)

Relates vapor pressure to temperature using the heat of vaporization. Assumes constant ΔHvap over the temperature range. Used for pressure-adjusted boiling point estimation.

Raoult's Law (Mixture Bubble Point):

∑ zi × Ki = 1   where   Ki = Pvap,i / P

At the bubble point, the sum of each component's mole fraction times its K-value equals unity. K-values are estimated from the ratio of pure-component vapor pressure to system pressure.

Quick Reference

Pressure Effect: Higher pressure raises the boiling point. The Clausius-Clapeyron equation estimates this shift using the heat of vaporization.
Mixtures: Bubble point is the temperature where the first vapor bubble forms. Dew point is where the first liquid droplet condenses. The region between is the two-phase envelope.
Critical Point: Above the critical temperature and pressure, distinct liquid and vapor phases do not exist. The substance becomes a supercritical fluid.