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.
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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
First, you will make a short practice entry to recognize the display, the pauses, and the button that decreases volume. During this first entry, you do not need to copy the full series onto paper or complete the assessed table yet. Data collection begins in the next phase, where you will open the lab again and enter each pressure directly in the TEACH table.
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 video pauses so you can read the pressure before pressing the decrease button again. In this practice run you will rehearse the procedure; during the second entry you will record the full series.
Open the Boyle lab for practice
Open the Boyle lab with the lab button in this activity.
Choose the 60 mL syringe.
Start observing and identify the first stable pressure on the LabQuest display. For this practice, reading it is enough; you do not need to save it on a separate sheet.
Continue through two pauses. At each one, check which volume matches the reading, then press the 5 mL decrease button.
Practise replaying a pause or taking a screenshot if a value is hard to read. Then return to TEACH: you will collect the complete series in the next phase.
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 video pauses and what you will do if a pressure value is hard to read.
Record and process pressure-volume evidence
16 min
Now make a second entry into the lab: this is the data-collection run. You do not need a separate sheet. The TEACH table below is where you should save the readings. Its volumes are already filled in; each row matches one video pause, from 60 mL down to 20 mL.
During the run, enter each pressure in the row for its volume before pressing the decrease button again. Then calculate 1/V as 1 divided by volume and PV as pressure times volume. The LabQuest display may show decimal commas, such as 85,79 kPa; enter this as 85.79 in a numeric field. If a pressure is hard to read, replay the pause or say so in the note column instead of inventing a number.
Open the lab again to collect data
Open the lab again and choose the 60 mL syringe.
Start the run at 60 mL. Keep this activity available so you can return to the table.
At the starting reading and every pause, enter the pressure directly in the row for the matching volume.
Only after saving the reading, return to the lab and press the 5 mL decrease button. Continue to 20 mL.
Use the note column for any reading you had to replay or that remains unclear.
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.
Example 60 mL graph pattern
This example shows the pattern to look for. Your own points may not be identical, but P versus 1/V should be closer to a straight line than P versus V.
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 |
|---|---|---|---|
Imagine repeating the 60 mL run to improve the quality of your data. Would you pay special attention to the full run, one particular middle reading, or the most compressed endpoint? Choose one and justify it using the most uncertain row or the least consistent PV value in your table.