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Physics · Thermal · Gas laws
Boyle's law — P vs V at constant T
A sealed gas column has its volume changed by a piston, while a pressure gauge reads the gas pressure. Pressure goes up as you squeeze the gas down; their product PV stays roughly constant — that is Boyle's law.
volume of gas (drag piston)
V = 100.0 cm³ · P = 1.00 atm · PV = 100
Results table
| V (cm³) | P (atm) | PV | 1/V × 1000 |
|---|---|---|---|
| 25 | — | — | — |
| 33 | — | — | — |
| 50 | — | — | — |
| 67 | — | — | — |
| 100 | — | — | — |
Plot · P vs 1/V
Straight line through the origin confirms PV = constant.
Exam-style questions
1. Boyle's law states (constant T, fixed mass):
2. Which graph gives a STRAIGHT LINE THROUGH THE ORIGIN if Boyle's law holds?
3. Why must temperature be CONSTANT?
4. Gas occupies 60 cm³ at 1.5 atm. What volume at 3.0 atm (constant T)?