ChemistryQuantitative ChemistryA-Level

Molar Volume of Gas Calculator

The molar volume of a gas relates the volume occupied by a gas to the amount of substance in moles at a constant temperature and pressure.

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Volume (dm³)

Formula first

Overview

Under standard conditions such as room temperature and pressure (RTP), one mole of any ideal gas occupies a specific volume, typically 24 dm³. This equation allows chemists to convert between the physical space a gas occupies and the chemical amount of particles present. It serves as a fundamental bridge for stoichiometric calculations involving gases.

Symbols

Variables

V = Volume (dm³), n = Moles (mol), Vm = Molar Volume (dm³ mol⁻¹)

Volume (dm³)
Moles (mol)
mol
Vm
Molar Volume (dm³ mol⁻¹)

Apply it well

When To Use

When to use: Use this when you are given the volume of a gas at RTP and need to find the number of moles involved in a reaction, or vice-versa.

Why it matters: It is essential for designing chemical processes, such as determining the output of industrial gas reactions or analyzing gas emissions in environmental chemistry.

Avoid these traps

Common Mistakes

  • Using 22.4 dm³ (STP) instead of 24 dm³ (RTP) when the problem specifies room conditions.
  • Failing to convert cm³ to dm³ before applying the equation.

One free problem

Practice Problem

Calculate the number of moles of oxygen gas that occupy a volume of 48 dm³ at room temperature and pressure.

Volume (dm³)48 m^3
Molar Volume (dm³ mol⁻¹)24 m^3

Solve for:

Hint: Use n = V / Vm.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Clark, J. (2020). Calculations in AS/A Level Chemistry.
  2. Royal Society of Chemistry: Quantitative Chemistry Resources
  3. A-Level Chemistry, Edexcel/AQA Specification, Gas Laws Section
  4. Avogadro's Law Principles
  5. AQA/OCR/Edexcel A-Level Chemistry Specification