The Gas Laws of Boyle and Charles
Learn about the Gas Laws of Boyle and Charles.
Learn about the Ideal Gas Law.
Learn about the determination of chemical formulas.
In this laboratory exercise we will use Charles’ Law to predict how much a gas, namely Air, should
contract when cooled from 100
C to Room Temperature.
We will then measure how the much the gas
Finally, we will then assess whether or not any deviation between the predicted value
and the measured value is due to experimental error or a break-down of Charles’ Law.
Modern scientific chemistry developed out of alchemy during the early 1600's, when application
of the Scientific Method began to take hold.
This method, basically, dictates that Fundamental
Laws and Theories must find support in direct experimental observation.
The earliest chemists
to apply this method to the behavior of substances were Pneumatic Chemists studying the
chemistry and properties of gases.
Although the gases Hydrogen and Oxygen would not be
discovered and characterized for some time, considerable progress was made in studying the
effects of environmental changes upon gases in general.
, was discovered by
Henry Cavendish in 1766 and Oxygen, O
, was discovered by Joseph Priestly in 1775.)
These environmental changes involve the variation of the pressure (P), volume (V), temperature
(T) and amount (n) of the gas in a sample.
The variables P, V, T, and n define the State
gas and are referred to as State Variables.
Changes in the state of the gas will influence the
values of the state variables.
For instance, in order to lower the pressure of a gas, we may
increase its volume, decrease its temperature, or decrease the amount of gas present.
Or, we may
do a combination of these things.
Thus, relationships between the state variables are important
to understand if we wish to understand the behavior of the gas.
The first of these relationships to be established, was that between volume and pressure.
Boyle, working with an improved design for the Air Pump developed by Otto von Guericke,
studied the effect of increasing the pressure on a sample of Air.
… because an accurate experiment of this nature would be of great importance to the doctrine of
the Spring of Air, and has not yet been made (that I know) by any man; and because also it is more
uneasy to be made than one would think, in regard of the difficulty as well of procuring crooked
Tubes fit for the purpose, as of making a just estimate of the true place of the protuberant
surface; I suppose it will not be unwelcome to the reader to be informed, that after
some other tryals, one of which we made in a Tube whose longer leg was perpendicular, and the
other, that contained the air, parallel to the horizon, we at last procured a Tube of the figure
expressed in the scheme; which Tube, though of a pretty bigness, was so long, that the cylinder,
whereof the shorter leg of it consisted, admitted a list of Paper, which had before been divided into