van der waals equation
Very lowScientific/Technical
Definition
Meaning
A mathematical formula describing the behavior of real gases by accounting for the finite size of molecules and the attractive forces between them.
In thermodynamics and physical chemistry, an equation of state that modifies the ideal gas law to account for intermolecular forces (van der Waals forces) and molecular volume, making it more accurate for real gases under high pressure and low temperature.
Linguistics
Semantic Notes
This is a proper noun phrase (named after Dutch physicist Johannes Diderik van der Waals). It refers to a specific, singular concept in physical chemistry. Always written with 'van der Waals' capitalized as part of the proper name.
Dialectal Variation
British vs American Usage
Differences
No significant differences. The spelling and usage are identical in British and American scientific contexts.
Connotations
Strictly technical and academic; carries the same neutral, scientific connotation globally.
Frequency
Used exclusively in academic, scientific, and engineering fields (e.g., chemistry, physics, chemical engineering). Frequency is near-zero in general discourse.
Vocabulary
Collocations
Grammar
Valency Patterns
The van der Waals equation [verb: predicts, describes, accounts for] ...One can [verb: use, apply, solve] the van der Waals equation to ...Vocabulary
Synonyms
Neutral
Weak
Vocabulary
Antonyms
Usage
Context Usage
Business
Not used.
Academic
Central concept in undergraduate physical chemistry and thermodynamics courses, used in research papers and textbooks.
Everyday
Not used.
Technical
Used by chemists, physicists, and engineers when modeling real gas behavior, e.g., in process design or high-pressure systems.
Examples
By Part of Speech
adjective
British English
- The van der Waals correction terms are essential.
- We studied the van der Waals constants a and b.
American English
- The van der Waals correction terms are critical.
- We studied the van der Waals constants a and b.
Examples
By CEFR Level
- The van der Waals equation is more complex than the ideal gas law.
- Scientists use the van der Waals equation for real gases.
- The van der Waals equation introduces two empirical constants to account for molecular volume and intermolecular attractions.
- By applying the van der Waals equation, we obtained a more accurate prediction of the gas's pressure under those conditions.
Learning
Memory Aids
Mnemonic
Think: 'Real gases aren't ideal; van der Waals forces are real, and his equation accounts for them.' The equation adds correction terms (a and b constants) to the ideal gas law.
Conceptual Metaphor
A more realistic map (the equation) for a bumpy, crowded territory (real gas behavior), compared to a simple, perfect map (ideal gas law) for a flat, empty plain.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- The phrase 'van der Waals' is a transliterated proper name and should not be translated. It remains 'уравнение Ван-дер-Ваальса' (uravneniye Van-der-Vaal'sa).
- Avoid confusing it with 'Van der Waals forces' (силы Ван-дер-Ваальса), which are the intermolecular forces the equation describes.
Common Mistakes
- Incorrect capitalization: writing 'Van Der Waals' or 'van der waals'. Correct: 'van der Waals'.
- Using it as a plural: 'van der Waals equations' (it is one specific equation).
- Misplacing the apostrophe: 'van der Waal's equation' (incorrect; no apostrophe).
Practice
Quiz
What does the van der Waals equation specifically account for that the ideal gas law does not?
FAQ
Frequently Asked Questions
Johannes Diderik van der Waals was a Dutch physicist who won the Nobel Prize in Physics in 1910 for his work on the equation of state for gases and liquids.
Use it when dealing with real gases under conditions of relatively high pressure and/or low temperature, where intermolecular forces and molecular volume become significant, causing deviations from ideal behavior.
'a' is a constant that corrects for the attractive forces between molecules (it increases the predicted pressure). 'b' is a constant that corrects for the finite volume occupied by the molecules themselves (it decreases the available volume).
No, it is a significant improvement over the ideal gas law but still an approximation. More complex equations of state (e.g., Peng-Robinson, Redlich-Kwong) are often used for greater accuracy in industrial applications.