A student investigates the relationship between the pressure and volume of a sealed gas syringe.
She takes readings of the volume as she increases the pressure (loading) and as she decreases the pressure (unloading).
Her results are shown in the table below:
| Pressure (10 kPa) | Volume of gas (loading) (cm3\text{cm}^3cm3) | Volume of gas (unloading) (cm3\text{cm}^3cm3) | Average (mean) volume (cm3\text{cm}^3cm3) |
|---|---|---|---|
| 120 | 49 | 51 | 50.0 |
| 100 | 59 | 61 | 60.0 |
| 80 | 77 | [missing] | 76.0 |
| 60 | 98 | 100 | 99.0 |
| 50 | 119 | 121 | 120.0 |
Calculate the missing unloading volume of gas at a pressure of 80 kPa.
Suggest one reason why the student takes readings whilst pressure is both increasing and decreasing.
The student concludes that her data validates Boyle's Law (p×V=constantp \times V = \text{constant}p×V=constant) for a fixed mass of gas.
Show calculations for at least three different pressures to evaluate whether the data supports her conclusion.