loschmidt's number
Very LowAcademic / Technical / Scientific
Definition
Meaning
A physical constant equal to the number of molecules (or atoms) in one cubic centimetre of an ideal gas at standard temperature and pressure (STP), approximately 2.6868 x 10²⁵ per m³.
Historically significant as the first accurate measurement of the size of molecules. It is distinct from the Avogadro constant, which is the number of particles per mole. Sometimes used interchangeably with 'Loschmidt constant' in modern usage.
Linguistics
Semantic Notes
The term is deeply historical and specific to physics and chemistry. It is often conflated with the Avogadro constant, but they are numerically different and relate to different standard conditions. Its usage is now largely historical or pedagogical.
Dialectal Variation
British vs American Usage
Differences
No significant differences in meaning or usage. Spelling may vary for the possessive ('Loschmidt's' vs. 'Loschmidts') but the former is standard.
Connotations
Identical in both variants—purely technical and historical.
Frequency
Extremely rare in both dialects, confined to specialised physics or chemistry texts, or historical discussions.
Vocabulary
Collocations
Grammar
Valency Patterns
[Subject] calculates Loschmidt's number.Loschmidt's number [verb] approximately 2.69e25 per cubic metre.The experiment yielded a value for Loschmidt's number.Vocabulary
Synonyms
Neutral
Weak
Usage
Context Usage
Business
Never used.
Academic
Used in specialised historical or pedagogical contexts in physics/chemistry to discuss the development of atomic theory.
Everyday
Never used.
Technical
Precise term in physics and physical chemistry for a specific constant; may appear in older literature or foundational papers.
Examples
By CEFR Level
- Loschmidt's number is important in the history of science.
- Scientists use Loschmidt's number to understand gases.
- The accurate determination of Loschmidt's number in the 19th century provided crucial evidence for the particulate nature of matter.
- While the Avogadro constant is more common today, Loschmidt's number remains a key result in kinetic theory.
Learning
Memory Aids
Mnemonic
Think: 'Loschmidt LOOKED and counted the molecules in a small cube at standard conditions.'
Conceptual Metaphor
A COUNT OF INVISIBLE ENTITIES (making the microscopic measurable).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Не путать с 'числом Авогадро' (Avogadro constant). Число Лошмидта — это количество молекул в единице объёма, а число Авогадро — в одном моле.
Common Mistakes
- Using it interchangeably with the Avogadro constant.
- Forgetting the possessive 's'.
- Misspelling 'Loschmidt' (e.g., Loschmid, Losmidt).
Practice
Quiz
What is Loschmidt's number?
FAQ
Frequently Asked Questions
No. Loschmidt's number is the number of particles per unit volume (at STP), while the Avogadro constant is the number of particles per mole. They are related but numerically different.
Johann Josef Loschmidt (1821-1895) was an Austrian scientist who made the first estimate of the size of air molecules and consequently this constant.
Almost exclusively in historical scientific texts, advanced physics/chemistry textbooks discussing the development of atomic theory, or very specialised technical papers.
The Avogadro constant and standard conditions defined by IUPAC have superseded it for most modern scientific work, making Loschmidt's number a historical curiosity.