Molar gas volume: The volume occupied by one mole of any gas at a specified temperature and pressure. At RTP this is 24 dm³/mol (24,000 cm³/mol).
RTP (Room Temperature and Pressure): The conditions used in GCSE gas calculations — 20°C (293 K) and 1 atmosphere (101 kPa). All gas volumes of 24 dm³/mol apply at these conditions.
dm³: Cubic decimetre — the same as one litre. 1 dm³ = 1000 cm³. Gas volumes are commonly given in either dm³ or cm³; always check which unit is needed.
Volume = moles × 24: The key formula at RTP. Can also be written as moles = volume ÷ 24 (when volume is in dm³).
This definitions covers Key Definitions within Gas Volume for GCSE Chemistry. Topic 19: Gas Volume It is section 5 of 11 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Practice questions for Gas Volume
What is the molar gas volume at RTP (room temperature and pressure)?
Explain why the molar gas volume of 24 dm³/mol is only valid at RTP.