Pressure – Temperature
Relationship in Gases
Chem
I
PURPOSE: Using your data and graph, you will
determine what kind of mathematical relationship exists between the pressure
and absolute temperature of a confined gas.
PROCEDURE: 1.
Submerge 125 ml Erlenmeyer flask into a water bath.
2.
Heat water, stir water with temperature probe to distribute
the
heat as evenly
as possible.
3.
Start collecting data.
Click collect
4.
Once a temperature is constant, click keep
Collect 5 temperature points. Try to obtain temperatures that are 10
degrees apart from each other.
Example: approximately (not exactly) 50, 60, 70, 80, 90
DATA:
Pressure
(atm)

Temperature
(^{o}C)

Temperature
(K)

Constant,
k
(P/T
or P * T)





















ANALYSIS:
 Build a graph of pressure versus temperature (K).
 In order to perform this experiment, what two
experimental factors were kept constant? (Help)
 Based on the data and graph that you obtained for
this experiment, express in words the relationship between gas pressure
and temperature. (Help)
 Explain the relationship using the concepts of
molecular velocity and collisions of molecules. (Help)
 Write an equation to express the relationship between
pressure and temperature (K). Use
the symbols P, T, and k (Help)
 One way to determine if a relationship is inverse or
direct is to find a proportionality constant, k, from the data. If this relationship is direct, k =
P/T. If it is inverse, k =
P*T. Based on your answer to
Question 5, choose one of these formulas and calculate k for the five
ordered pairs in your data table.
Show the answer in the fourth column of the Data and calculations
table. How “constant” were your
values?
 According to this experiment, what should happen to
the pressure of a gas if the Kelvin temperature is doubled? Check this assumption by finding the
pressure at –73^{o}C (200 K) and at 127^{o}C (400 K) on
your graph of pressure versus temperature. How do these two pressure values compare?
EXTENSION:
 The data that you have collected can also be used to
determine the value for absolute zero on the Celsius temperature
scale. Instead of plotting
pressure versus Kelvin temperature like we did previously, this time you
will plot Celsius temperature on the yaxis and pressure on the
xaxis. Since absolute zero is the
temperature at which the pressure theoretically becomes equal to zero, the
temperature where the regression line (the extension of the
temperaturepressure curve) intercepts the yaxis should be the Celsius
temperature value for absolute zero.