
Aim: to verify Charles’ Law and find the Absolute
Zero of Temperature 
See Why a Gas Exerts a Pressure,
The Gas Laws 

Method 
Set up apparatus similar to that shown in the
diagram below. 

The temperature of the gas can
not be measured directly; we assume that the temperature
of the gas is the same as the temperature of the water. 
This is why the experiment
takes quite a while, you have to wait a long time for
the gas inside the capillary tube to attain the same
temperature as the water. 
The volume of the gas will also not be
measured but we will assume that the tube is of
uniform crosssectional area. 
This means that changes in volume are directly
proportional to changes in the length of the
air column. 

Note that this simple
arrangement guarantees that the results are measured at
constant pressure, an important stipulation of the law
being investigated. 
The pressure of the gas will
remain (essentially) the same as the atmospheric
pressure throughout the experiment. 

The concentrated H_{2}SO_{4}
is used for two reasons: 
1. you need something to trap
the air in the tube (duh... obviously!) 
2. it has the effect of drying
the air (that is, removing any water vapour). 

Analysis of results: 
Plot a graph of length of air column against temperature on the
largest scales possible. 
Draw the best fit straight line and find its
slope and the intercept on the volume
axis. 
The equation of this line has the form 

where a is the slope and b is the
intercept on the volume axis. 

To find a value for the absolute zero of
temperature, we simply have to find the value of T
which corresponds to zero volume (or zero length of air
column). 
When L = 0, we have 
