The Gaseous State
Learn and apply The Gaseous State in the published Chemistry course sequence.
Learning goals
- Ideal Gas Model and pV = nRT
- Dalton’s Law and Partial Pressures
- Real Gases and Deviations
What You’ll Learn
- State the basic kinetic-theory assumptions for an ideal gas.
- Use pV = nRT with consistent units, including determining relative molecular mass, Mᵣ.
- Apply Dalton’s law to determine partial pressures in gas mixtures.
- Explain why gases approach ideal behaviour at low pressure and high temperature, and why the model is limited at very high pressure and very low temperature.
The Gaseous State is prescribed in H2 9476. H1 8873 uses reacting gas volumes within Stoichiometry but does not require the general gas equation as a topic.
Lessons (Recommended Order)
- Ideal Gas Model and pV = nRT — learn the model assumptions, unit discipline and Mᵣ workflow.
- Dalton’s Law and Partial Pressures — separate a total pressure into component pressures before calculating.
- Real Gases and Deviations — identify which ideal assumption fails under extreme conditions.
Follow this order on a first pass. For revision, choose the lesson matching the evidence in the question: equation data, a mixture, or a deviation from ideality.
Quick Reference
| Question evidence | First move | Essential check |
|---|---|---|
| one gas with p, V, T | use pV = nRT | T in K; p and V match R |
| mass and gas data | find n, then M = m/n | report Mᵣ without a unit |
| gas mixture | use pᵢ = xᵢ pₜₒₜₐₗ | ∑ xᵢ = 1 and ∑ pᵢ = pₜₒₜₐₗ |
| gas collected over water | subtract p_H₂O | use the dry-gas pressure in pV = nRT |
| low pressure, high temperature | gas approaches ideality | particles are far apart; attractions matter less |
| very low temperature | attractions become significant | pressure may be below the ideal prediction |
| very high pressure | molecular volume becomes significant | free volume is smaller than container volume |
Useful unit identity: 1 kPa dm³ = 1 J, so R = 8.31 is consistent with kPa and dm³ as well as Pa and m³.
Hub Quiz
Use the Gaseous State hub quiz after all three lessons. For written working and explanation practice, continue to structured Gaseous State practice.
Practise
Work through questions with marking and feedback as you learn.
About 10 minutes
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Questions are picked at random each time you start. You'll see the answer after each question. It's for practice only and doesn't count towards mastery.
Recent attempts
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No completed attempts are saved yet.
Beyond the syllabus: optional enrichment that does not count towards your progress.
Practise after feedback
After a check, practise the skills it showed you need to work on.
About 10 minutes
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Questions are picked at random each time you start. You'll see the answer after each question. It's for practice only and doesn't count towards mastery.
Recent attempts
History is stored only in this browser.
No completed attempts are saved yet.
Beyond the syllabus: optional enrichment that does not count towards your progress.
Check what I know
Start here to see which parts you already know.
About 8 minutes
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Answer 3 short questions. It shows what to work on next and doesn't count towards mastery.
Recent attempts
History is stored only in this browser.
No completed attempts are saved yet.
Beyond the syllabus: optional enrichment that does not count towards your progress.
Check my progress
When you feel ready, answer on your own to show what you can do.
About 10 minutes
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Answer 3 questions. You'll see your score, the answers and explanations at the end. Your result can count towards your course progress.
Recent attempts
History is stored only in this browser.
No completed attempts are saved yet.
Beyond the syllabus: optional enrichment that does not count towards your progress.
Check again
After practising what your progress check showed, check those skills again.
About 10 minutes
Time is up, but your answers have not been submitted yet. Check your connection and try again.
Answer 3 questions. You'll see your score, the answers and explanations at the end. Your result can count towards your course progress.
Recent attempts
History is stored only in this browser.
No completed attempts are saved yet.
Beyond the syllabus: optional enrichment that does not count towards your progress.
Review
Come back later to see whether your learning has lasted.
About 10 minutes
Time is up, but your answers have not been submitted yet. Check your connection and try again.
Answer 3 questions. You'll see your score, the answers and explanations at the end. A scheduled review counts towards your course progress only when it is due.
Recent attempts
History is stored only in this browser.
No completed attempts are saved yet.
Beyond the syllabus: optional enrichment that does not count towards your progress.
Connections and targeted revision
Use Gaseous State reasoning again in Chemical Equilibria, where gaseous mixtures are expressed through partial pressures and Kₚ.
If one error persists, return to the matching lesson rather than rereading the whole hub:
- units or Mᵣ → Ideal Gas Model;
- mole fraction or wet gas → Dalton’s Law;
- failed assumptions → Real Gases and Deviations.