ideal gas law
C1+Technical / Academic
Definition
Meaning
A fundamental equation in physics and chemistry, PV = nRT, that describes the relationship between pressure, volume, amount, and temperature of an ideal gas.
A mathematical model and state equation used to approximate the behaviour of real gases under many conditions, based on the kinetic theory of gases and the assumptions of negligible molecular volume and no intermolecular forces.
Linguistics
Semantic Notes
Refers to both the specific formula and the underlying physical law it represents. The term is used as a compound noun, often treated as a single concept.
Dialectal Variation
British vs American Usage
Differences
No significant lexical differences. The spelling of derived terms (e.g., idealise/idealize) follows regional conventions.
Connotations
Identical technical/scientific connotations in both varieties.
Frequency
Equally frequent in scientific/engineering contexts in both regions.
Vocabulary
Collocations
Grammar
Valency Patterns
[Subject] obeys the ideal gas law.The ideal gas law [verb] that PV = nRT.According to the ideal gas law, ...Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “As predictable as the ideal gas law.”
Usage
Context Usage
Business
Rare. Might appear in technical industries (e.g., energy, engineering) in reports or proposals.
Academic
Core terminology in physics, chemistry, and engineering courses and textbooks.
Everyday
Virtually never used. A layperson would simply refer to 'gas pressure' or 'gas behaviour'.
Technical
Primary usage. Found in research papers, lab reports, technical manuals, and engineering calculations.
Examples
By Part of Speech
verb
British English
- We can idealise the gas behaviour to apply the simple formula.
American English
- We can idealize the gas behaviour to apply the simple formula.
adverb
British English
- The system behaved ideally, conforming to the law.
American English
- The system behaved ideally, conforming to the law.
Examples
By CEFR Level
- Scientists use the ideal gas law for many calculations.
- The ideal gas law, PV=nRT, is derived from combining several simpler gas laws.
- While the ideal gas law provides a useful approximation, it breaks down under conditions of high pressure where intermolecular forces become significant.
Learning
Memory Aids
Mnemonic
Please, Vacate My Room - it's Tense! (Pressure, Volume, Moles, R, Temperature).
Conceptual Metaphor
A rulebook for gas behaviour; a mathematical map describing gas properties.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid direct calque of 'law' as only 'закон'. In this context, 'уравнение' (equation) or 'формула' is often more precise.
- Do not translate 'ideal' as 'идеальный' in a philosophical sense; here it means 'theoretical' or 'perfect' ('идеальный газ' is correct).
- The word order is fixed; translating as 'law of ideal gas' changes the nuance.
Common Mistakes
- Incorrect formula recall (e.g., P/V = nRT).
- Using it for liquids or solids.
- Applying it to real gases under high pressure/low temperature without correction.
- Pronouncing 'gas' with a /z/ in 'law' (it remains /s/).
Practice
Quiz
Which of the following is NOT an assumption of the ideal gas law?
FAQ
Frequently Asked Questions
R is the universal gas constant. Its value is approximately 8.314 J/mol·K.
No. It is an excellent approximation for most gases at relatively high temperatures and low pressures, but it becomes inaccurate for real gases under high pressure or near their condensation point.
It was not discovered by a single person. It is a combination of earlier empirical gas laws (Boyle's, Charles's, Avogadro's) and was first stated in its modern form by Benoît Paul Émile Clapeyron in 1834.
Yes, through Dalton's Law of Partial Pressures. The total pressure is the sum of the partial pressures, and 'n' represents the total number of moles of gas particles in the mixture.