Investigating the Effect of Temperature on the Volume of a Gas
Aim: To investigate the effect of temperature on the volume of a gas,
given that the pressure acting on the gas is fixed.
Hypothesis: According to CharlesÂ’s Law, the volume of a given amount
of gas is directly proportional to the absolute temperature when the
pressure is constant. Thus, it is expected that as the temperature of
the gas increases, its volume
will increase also at a constant rate.
When the temperature is increased, the particles in the gas gain more
and as a result, the particles move faster and quicker
and thus, the particles bombard each other more frequently. Because of
this, the pressure exerted by the gas on its surroundings increase,
creating an increase in the volume of the gas.
* Input(Independent): Temperature T/Â°C
* Output(dependent): length of air column, L/cm
* Controlled Variables: pressure and mass of gas inside capillary
30 cm ruler
Concentrated Sulfuric acid
* Heat the end of the glass tube so as to close it. The tubeÂ’s end
will melt and close. Make sure the end is blocked very well.
* Using a syringe needle, inject approximately 1cmÂ³ of Sulfuric acid
into the blocked glass tube. Refer to the diagram.
* Inject the Sulfuric acid gradually, creating an air column as
shown in the above diagram.
* Be careful, Sulfuric acid is a dangerous dehydrating agent that
will burn your skin.
* Measure the diameter of the glass tubeÂ’s opening.
* Once this is done, set up the clamp stand and beaker as shown in
the above diagram. Using the 30 cm ruler, measure the length of
the air column at room temperature. Record your readings.
* Gradually, heat the water in the beaker and at certain
temperatures, measure the changing length of the air column.
* Carry this out for a range of different temperature readings and
record your obtained values in a table.
The following table summarizes the obtained results. The temperatures
are recorded in both Celsius and Kelvin Scales. The table allows us to
compare how the length of air column changes with the increase in
T(K)= T(Â°C)+ 273.15
Length of air column L/cm Â±0.10
Data Processing and Presentation:
To analyze how the increase in temperature affects the volume of a
gas, the volume must first be calculated. We do this using the above
table and the following formula: V=Ï€rÂ²L where V=volume, Ï€=pie=3.124,
r=radius of glass tube, L=length of air column.
The radius of the glass tube is too small to measure with a normal 30
cm ruler so we assume that the radius=0.05cm
The following table represents the change in volume of the gas as the
temperature is increased.
Length of air column L/cm Â±0.10
Volume of gas V/cmÂ³ Â± 0.0008
To further investigate how the increase in temperature affects the
volume of a gas; a graph is drawn to show the relation between the
Temperature and volume of a gas.
Conclusion and Evaluation:
From the results obtained, we can conclude that the volume of a gas
does increase as the temperature is increased. By Comparing the data
collected in the experiment, we can see that when the temperature was
raised from 301K to 353K, the volume of the gas also increased from
approximately 0.0289 cmÂ³ to 0.032 cmÂ³. This is evidence that the
volume and temperature are directly proportional. However, the graph
drawn does not greatly demonstrate the constant increase in volume.
The straight line obtained is not exact and we cannot base our
conclusion on this. To further investigate this property, more results
must be obtained. Nevertheless, it is evident that the volume of a
given amount of gas is directly proportional to the absolute
temperature when the pressure is constant.
Improving the Experiment:
It would be useful to measure the radius of the glass tube using a
micrometer. This would give exact values. Moreover, when the glass
tube is removed from the beaker to record the air column, the
temperature falls down rapidly. This causes a difficulty in recording
exact results. Next time, 2 clamp stands should be used, so as to make
it possible to leave the ruler next to the glass tube and not move it
out of the water. The readings could be done while the glass tube
stays in the water.