8 Donna had heard that the pressure of a constant volume of gas is directly proportional to its
temperature.
To test this for herself, Donna observed how the pressure in a tube changed as the gas inside was
heated. Her results are shown in the table:
Temperature (T°C)
Pressure (P x 105 Pa)
5 10 15 20
25 30 35
3.22 3.28 3.33 3.39 3.45 3.51 3.57
a Obtain the power model which best fits the data. Explain
why P is not directly proportional to T.
b
Donna's friend Penny suggests that the temperatures should
be recorded in kelvin (K) rather than degrees Celsius.
i Redraw the table with the temperatures recorded in
kelvin.
ii Obtain the power model which best fits the data.
Is it now reasonable to conclude that pressure and
temperature are directly proportional? Explain your
answer.
To convert temperatures
from °C to K, add 273.15.