M

Molar Volume

V_m = 22.414 L/mol (ideal gas at STP); V_m = M/ρ (liquids/solids)
Quick Reference
Formula / NotationV_m = 22.414 L/mol (ideal gas at STP); V_m = M/ρ (liquids/solids)
Also Known AsMolar volume, V_m, specific molar volume, 22.4 L/mol (STP approximation)

What is Molar Volume?

The volume occupied by one mole of a substance. At STP (0°C, 1 atm), one mole of an ideal gas occupies 22.4 L. At standard conditions (25°C, 1 bar), the molar volume is 24.8 L. Molar volume of solids and liquids varies considerably from substance to substance.

Formula & Notation

V_m = 22.414 L/mol (ideal gas at STP); V_m = M/ρ (liquids/solids)

Other Names / Synonyms: Molar volume, V_m, specific molar volume, 22.4 L/mol (STP approximation)

Properties & Characteristics

Molar volume (V_m) is the volume occupied by one mole of a substance. For an ideal gas at STP (0°C, 1 atm): V_m = RT/P = 22.414 L/mol. At SATP (25°C, 1 bar): V_m = 24.79 L/mol. For liquids and solids, molar volume = molar mass / density. Molar volumes of liquids and solids are much smaller than gases (water: 18.02 mL/mol). Molar volume is an intensive property and provides insight into intermolecular interactions.

Uses & Applications

Molar volume is used in: gas law calculations, converting between moles and volume of gases, comparing packing efficiency of solids (partial molar volumes in solutions), designing gas storage systems, and in electrochemistry (volume changes during electrode reactions).

Safety Information

No direct safety concern for the concept. The large molar volume of gases (>22 L/mol) compared to liquids (<1 L/mol) means that small volumes of liquid can produce very large volumes of gas — relevant to understanding the hazard of rapid liquid-to-gas transitions (liquid nitrogen spills, aerosol can explosions).

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

Key Facts

Term Molar Volume
Formula V_m = 22.414 L/mol (ideal gas at STP); V_m = M/ρ (liquids/solids)
Synonyms Molar volume, V_m, specific molar volume, 22.4 L/mol (STP approximation)

Frequently Asked Questions

The volume occupied by one mole of a substance. At STP (0°C, 1 atm), one mole of an ideal gas occupies 22.4 L. At standard conditions (25°C, 1 bar), the molar volume is 24.8 L. Molar volume of solids and liquids varies considerably from substance to substance.

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