Engineering English
Raoult's Law
Chemical Engineering · Last updated: July 30, 2026 · How this entry was written
Definition: Raoult's law states that the partial vapor pressure of a component in an ideal solution is equal to the product of its mole fraction and its vapor pressure in the pure state. It is used to describe the vapor-liquid equilibrium of ideal mixtures.
Example in context
“In our distillation column design, we applied Raoult's law to estimate the vapor-phase composition from the liquid mole fractions.”
“Damıtma kolonu tasarımımızda, sıvı mol fraksiyonlarından buhar fazı bileşimini tahmin etmek için Raoult yasasını uyguladık.”
Where engineers use it
Raoult's law is foundational in vapor-liquid equilibrium calculations for ideal mixtures. Engineers apply it in distillation design, flash calculations, and where non-ideality is negligible. It helps predict phase compositions and boiling points.
Practice: can you use “Raoult's Law” at work?
You are given a mixture of benzene and toluene at 80°C. The pure vapor pressures are 780 mmHg and 400 mmHg respectively. Determine the liquid composition that yields a vapor of 0.6 mole fraction toluene.
Show a model answer
“Calculate the equilibrium vapor composition using Raoult's law.”
“Raoult's Law” in 21 languages
| English | Raoult's Law |
|---|---|
| Turkish | Raoult yasası |
| French | loi de Raoult |
| German | Raoultsches Gesetz |
| Spanish | ley de Raoult |
| Chinese | 拉乌尔定律 |
| Arabic | قانون راؤول |
| Portuguese | Lei de Raoult |
| Russian | Закон Рауля |
| Japanese | ラウールの法則 |
| Italian | legge di Raoult |
| Vietnamese | Định luật Raoult |
| Hindi | राउल्ट का नियम |
| Thai | กฎของราอูลท์ |
| Indonesian | Hukum Raoult |
| Korean | 라울의 법칙 |
| Bengali | রাউল্টের সূত্র |
| Dutch | Wet van Raoult |
| Swedish | Raoults lag |
| Finnish | Raoultin laki |
| Ukrainian | Закон Рауля |
Frequently asked questions
What does Raoult's Law mean in engineering?
Raoult's law states that the partial vapor pressure of a component in an ideal solution is equal to the product of its mole fraction and its vapor pressure in the pure state. It is used to describe the vapor-liquid equilibrium of ideal mixtures. In Chemical Engineering, the term carries a usage-frequency rating of 10/10 in the Engineering English library.
How do you pronounce Raoult's Law?
Raoult's Law is pronounced /ˈraʊlts lɔː/ (IPA). The Engineering English app plays audio for the term and checks your pronunciation with speech recognition.
How is Raoult's Law used in a sentence?
Example from an engineering context: “In our distillation column design, we applied Raoult's law to estimate the vapor-phase composition from the liquid mole fractions.”
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