Knowledge Organiser: Gas Volumes
Part of Gas Volume · GCSE GCSE Chemistry revision
This topic summary covers Knowledge Organiser: Gas Volumes within Gas Volume for GCSE Chemistry. Topic 19: Gas Volume It is section 11 of 11 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 11 of 11
Practice
20 questions
Recall
20 flashcards
Knowledge Organiser: Gas Volumes
Key Terms
- RTP: 20°C and 1 atmosphere pressure
- Molar gas volume: 24 dm³/mol at RTP
- Volume = n × 24 (dm³)
- Moles = V ÷ 24
- 1 dm³ = 1000 cm³
Must-Know Facts
- All gases: 24 dm³/mol at RTP
- Particle size does not affect molar volume
- Multi-step route: mass → moles → ratio → volume
- Use 24 (not 22.4) for GCSE calculations
- Always convert cm³ ÷ 1000 to get dm³ first
Key Equations
- Volume (dm³) = moles × 24
- Moles = volume (dm³) ÷ 24
- 1 dm³ = 1000 cm³ (always convert before calculating)
- Molar gas volume at RTP = 24 dm³/mol
Common Mistakes
- Using 22.4 dm³/mol instead of 24: At GCSE, RTP is 20°C and 1 atm — molar volume is 24 dm³/mol (22.4 is used at 0°C/STP, not GCSE)
- Forgetting to convert cm³ to dm³: Divide cm³ by 1000 before using volume = moles × 24
- Thinking heavier gases occupy less volume: All gases occupy the same molar volume at RTP — 24 dm³ per mole regardless of Mr
- Skipping the mole ratio step: In multi-step calculations, use the equation ratio to convert moles of one gas to moles of another before calculating volume
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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.
Quick Recall Flashcards
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