A

Avogadro's Law

V ∝ n (at constant T and P); V/n = k
Quick Reference
Formula / NotationV ∝ n (at constant T and P); V/n = k
Also Known AsAvogadro's hypothesis; Avogadro's principle; equal volumes equal moles law; molar volume principle

What is Avogadro's Law?

Avogadro's law states that equal volumes of all gases, at the same temperature and pressure, contain equal numbers of molecules. Equivalently, the volume of a gas is directly proportional to the amount of gas (in moles) at constant temperature and pressure. This principle forms the basis of the molar volume concept (22.4 L/mol at STP).

Formula & Notation

V ∝ n (at constant T and P); V/n = k

Other Names / Synonyms: Avogadro's hypothesis; Avogadro's principle; equal volumes equal moles law; molar volume principle

Properties & Characteristics

V/n = k (constant at fixed T and P); V₁/n₁ = V₂/n₂; at STP (0°C, 1 atm): 1 mol any ideal gas = 22.4 L; applies to all ideal gases regardless of identity; basis of molar volume concept; component of ideal gas law (PV = nRT)

Uses & Applications

Calculating gas volumes in chemical reactions; stoichiometry of gaseous reactions; determining molar volumes; relating gas amounts to volumes in industrial processes; foundational principle in gas law calculations

Safety Information

No direct hazard — a gas law relationship. Specific gases involved may be hazardous; always check SDS for gases used.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Avogadro's Law
Formula V ∝ n (at constant T and P); V/n = k
Synonyms Avogadro's hypothesis; Avogadro's principle; equal volumes equal moles law; molar volume principle

Frequently Asked Questions

Avogadro's law states that equal volumes of all gases, at the same temperature and pressure, contain equal numbers of molecules. Equivalently, the volume of a gas is directly proportional to the amount of gas (in moles) at constant temperature and pressure. This principle forms the basis of the molar volume concept (22.4 L/mol at STP).

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