Find the pressure–temperature relationship at fixed volume
Three steps, the way the exam actually works: work through the lab, write down your own measurements, then answer a 6-point free response. What you recorded goes to the grader with your writing, so a conclusion that does not follow from your own numbers will cost you the point — exactly as it would with a real reader.
Predict before you look
- Pressure comes from particles striking the walls. Name the two features of those collisions that set the pressure — how often they happen, and what else?
- The ideal gas law is PV = nRT. With V and n held fixed, rearrange it to show exactly what P is proportional to.
Nothing to submit here — these are to think through, so the prediction below is an informed one rather than a guess.
Commit to an answer now. It is not graded and being wrong costs nothing — the point is to have something specific to reconcile against once you have the data.
Answer every prediction to unlock the lab. A sentence is enough.
Run the investigation
Predictions first
The procedure and the simulation unlock once you have committed above. Observing before predicting is how a wrong intuition survives a lab intact.
Record what you measured
These are your numbers, not ours. The grader sees them, so your conclusions have to follow from what you actually recorded.
| Relative pressure at T = 0.50 | |
|---|---|
| Relative pressure at T = 1.00 | |
| Relative pressure at T = 1.50 | |
| Relative pressure at T = 2.00 |
Answer the free response
You held the volume and the amount of gas constant and varied only the temperature. (a) State the mathematical relationship between pressure and temperature that your data support, and cite specific values from your table as evidence. (b) Explain the relationship using the kinetic molecular theory, addressing both how often particles strike the walls and how hard they strike. (c) Show how your relationship follows from the ideal gas law. (d) Predict what happens to the pressure if you now increase the container volume while holding temperature constant, and explain why in terms of collisions with the walls.
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