An industrial chemist is testing the thermal properties of a new gaseous coolant. A fixed mass of the gas is sealed inside a rigid, constant-volume steel vessel equipped with a high-precision digital pressure transducer and a thermocouple.
The vessel is submerged in a liquid bath, and the temperature is adjusted. The chemist records the temperature of the bath, θ\thetaθ, and the absolute pressure of the gas, ppp.
The table below shows the data obtained:
| θ\thetaθ | ppp | p/(θ+273.15)p / (\theta + 273.15)p/(θ+273.15) |
|---|---|---|
| 10.0 | 98.2 | 0.347 |
| 30.0 | 105.1 | 0.347 |
| 50.0 | 112.0 | 0.347 |
| 70.0 | 119.0 | 0.347 |
State what essential detail the chemist has omitted from the column headings of this table.