Teach lesson
Boyle's Law: pressure and volume from a real syringe run
Students use the UNED Boyle remote lab to read pressure from real video, calculate PV and 1/V, and decide whether pressure is inversely proportional to volume.
Learning Outcomes
Use a real Boyle remote-lab video to collect pressure-volume evidence.
Calculate 1/V and PV from consistent volume and pressure units.
Compare a curved pressure-volume graph with a linear pressure-vs-1/V graph.
Use live 60 mL syringe readings to evaluate how close PV is to constant.
Explain real-data uncertainty without rejecting the gas-law model too quickly.
Write a claim-evidence-reasoning conclusion about an inverse gas-law relationship.
Student activity preview
Activity Content
Preview only. In a class session, students can fill in responses and submit their work to the teacher.
Predict the inverse pattern
8 min
Boyle's law says that, for a fixed amount of gas at approximately constant temperature, pressure and volume should be inversely related. That does not mean pressure and volume make a straight line when plotted directly. It means the graph becomes easier to test when pressure is plotted against 1/V, and the product PV should stay approximately constant.
In this activity, pressure means how strongly the gas pushes on the syringe walls, measured in kPa. Volume means the space the gas occupies in the syringe, measured in mL. When volume gets smaller, the same gas is compressed into less space, so particles collide with the walls more often. That is why pressure rises.
An inverse relationship means one variable increases while the other decreases in a predictable way. For Boyle's law, the useful check is not "does pressure go up?" but "does pressure rise roughly like 1/V, and does PV stay nearly constant?"
The real Boyle observation screen
The pressure value comes from the LabQuest display in the video. The volume comes from the syringe setting and each decrease step.
Model to test
PV \approx \text{constant}
\qquad
P \propto \frac{1}{V}
Before opening the lab, predict what should happen to pressure when the syringe volume decreases. Your answer must mention fixed temperature, particle collisions or compression, and why the relationship is inverse rather than direct.
Which graph should be closest to linear if Boyle's law is a good model?
Use the syringe video deliberately
12 min
In this activity you will use the 60 mL syringe run. You will record pressure at 60, 55, 50, 45, 40, 35, 30, 25, and 20 mL, then use those readings to test Boyle's law.
Interface wording note
The lab introduction may mention pressure and temperature. For this Boyle run, focus on what you actually control and observe: the syringe volume changes, pressure is read from the LabQuest display, and temperature is treated as approximately constant.
Lab workflow
The experiment pauses so you can record the pressure before pressing the decrease button again.
Open the Boyle lab
Open the Boyle lab with the lab button in this activity.
Choose the 60 mL syringe.
Start observing. At the first stable pressure display, record the starting pressure. Read the pressure value in kPa shown on the LabQuest display in the video.
Each time the experiment pauses, record the pressure, then press the 5 mL decrease button.
Continue until the 20 mL endpoint. Use the video display as your evidence. If one reading is hard to read, replay the pause, use a screenshot, or mark that row as uncertain in the note column.
Which plan will produce a useful pressure-volume table?
Write a two-sentence plan for collecting readable pressure data. Include how you will handle the experiment pauses and what you will do if a pressure value is hard to read.
Record and process pressure-volume evidence
16 min
Use the 60 mL volume sequence already entered in the table. Each row represents one experiment pause: first the starting volume, then each 5 mL decrease. Use consistent units before calculating 1/V and PV. Calculate 1/V as 1 divided by the volume, and PV as pressure times volume.
The LabQuest display may show decimal commas, such as 85,79 kPa. For calculations and numeric fields, write that as 85.79 kPa. If a pressure is hard to read, replay the pause or mark the row as uncertain in the note column instead of inventing a number.
Boyle evidence table
Record pressure readings from the LabQuest display for the 60 mL run. Calculate 1/V and PV for every completed row. Use the note column for rows that were difficult to read.
| Step | Volume mL | Pressure kPa | 1/V 1/mL | PV kPa mL | Reading note |
|---|---|---|---|---|---|
Check your data table. State the volume range, the pressure range, and one pressure reading you are least confident about. Explain why that reading is less certain.
Choose one mid-range row from your table and calculate the PV product in kPa mL. Enter the numeric value and explain the calculation.
Graph the inverse relationship
14 min
The same pressure-volume data can tell two stories. P versus V should curve downward. P versus 1/V should be much closer to a straight line. This is why the graph choice matters.
For your graphs, first use the table columns volume, pressure, and 1/V. Make two scatter plots from the same table: P versus V, and P versus 1/V. In the second graph, put 1/V on the horizontal axis in 1/mL and pressure P on the vertical axis in kPa. You may make the graphs in a spreadsheet, on paper, or with another graphing tool.
Graph scaffold for your Boyle data
Use these empty axes as a scaffold. Plot your own table values before deciding which graph is closer to a straight line.
Your Boyle graphs
Attach a spreadsheet or PDF, add an image reference if you made the graphs on paper, or describe them in text. Include enough detail that a teacher can tell which values you used and whether P versus 1/V is close to linear.
Describe your graphs. Name the axes for the P versus 1/V graph, state that the data came from your table, and compare the shape of P versus V with P versus 1/V.
Compare P versus V with P versus 1/V. Which graph better supports Boyle's law, and why?
Treat real-data deviations scientifically
8 min
Real data do not have to be perfect to support a model. In a 60 mL syringe run, most PV products should be in a similar range, but one row may differ more than the others. That can come from reading difficulty, sensor behavior, or movement near the most compressed endpoint.
Choose the row in your table that least fits constant PV. Explain how you found it and give one plausible reason it might differ from the others.
Make the scientific claim
10 min
Your final answer should not just say "pressure goes up." It should explain why the relationship is inverse, what evidence supports that, and what uncertainty remains.
Write a claim-evidence-reasoning conclusion. Use your table, PV, and the P versus 1/V graph to decide whether the real Boyle lab supports Boyle's law.
In one sentence, explain the difference between "the data support Boyle's law" and "the data are perfect."
Compare class results
12 min
If your class shares results, compare the 60 mL runs from different groups. If you are working alone, use this phase as a short reflection on which row you would repeat. The important comparison is not who got the highest pressure; it is which data give the strongest inverse-model evidence.
Class comparison of Boyle runs
Each group contributes one summary row after completing its graph.
| Group | Volume range | PV range | Graph judgment |
|---|---|---|---|
If you could repeat one part of the 60 mL run, would you repeat the full run, a middle reading, or the most compressed endpoint? Justify the choice.