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.
📖 Key Definitions
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).
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.