Experiment 10
EXPERIMENTING WITH GAS LAWS
I.
Learning Objectives…
♦
To introduce the relationship between the pressure and the volume of a
confined gas.
(
Boyle's Law
)
♦
To investigate the relationship between the pressure and temperature of a
confined gas.
(
GayLussac's Law
)
♦
To investigate direct and inverse relationships using graphical analysis.
II.
Background Information
A gas is defined as the state of matter in which widely separated molecules move in a
random and chaotic fashion in a volume defined by the size of the container.
Four
quantities are used to describe gases:
pressure, volume, temperature, and quantity (moles).
The
ideal gas law
describes the relationship between these properties with an equation.
PV = nRT
where:
P = pressure (atm)
V = volume (L)
n = mole
T = temperature (K)
R = gas constant (0.0821 L
•
atm/K
•
mol)
Under standard conditions of temperature and pressure (273.15 K, 1.0 atm pressure), 1
mole of gas occupies 22.414 L for an
ideal gas
.
Substituting these values into the ideal gas
equation above, the gas constant (R) is 0.08206 L
•
atm/K
•
mol.
Experimentally, a value of
R can be determined for a gas by carefully measuring P, V, n, and T for a given sample of
gas and using the ideal gas equation to solve for R.
The objective of this experiment is to introduce two relationships that illustrate the
interrelated properties of gases.
First, the relationship between the pressure and volume of
a confined gas is investigated.
Historically, this relationship was first established by
Robert Boyle in 1662 and has since been known as
Boyle’s Law
.
The gas used in this
experiment is air (actually a mixture of gases), which has a molar mass of
28.96 g/mol
and
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document102
a density of
0.001185 g/mL
at room temperature (25
o
C, 273K).
In this experiment air is
first confined in a syringe connected to a pressure sensor.
Then, the volume of the syringe
is adjusted in 1 mL increments as the relative pressure exerted by the confined gas is
measured at each volume.
The pressure change is monitored using the pressure sensor
connected via the interface to a computer.
It is assumed that temperature remains constant
throughout the experiment.
Pressure and volume data is collected and plotted to determine
what mathematical relationship exists between the pressure and volume of a confined gas.
The second part of the experiment is to verify
GayLussac’s Law
.
In the early 1800’s,
Joseph GayLussac published his work describing the relationship between the pressure of
a gas and its temperature. Gas molecules are in constant motion and exert pressure via
collisions with the walls of their container.
The velocity and the number of collisions for
these molecules are affected when the temperature of the gas increases or decreases.
In
this experiment, the pressure and temperature of an air sample in an Erlenmeyer flask are
monitored with a pressure sensor and a temperature sensor.
The volume of the gas sample
and the number of molecules it contains are kept constant as the temperature is varied.
Subsequent data analysis illustrates the mathematical relationship existing between the
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '07
 n/a
 Erlenmeyer flask

Click to edit the document details