Untitled - Kelly Walsh High School

82 CHEMISTRY FOR THE UTTERLY CONFUSED
TABLE 5-1 Gas Laws
Name of Law Held Constant Variables Relationship
Combined gas law Amount (n) Pressure, volume, (P 1V 1)/T 1
and temperature (K) (P 2V 2)/T 2
Boyle’s law Temperature (T) Volume and pressure P 1V 1 P 2V 2
and amount (n)
Charles’ law Pressure (P) and Volume and V 1/T 1 V 2/T 2
amount (n) temperature (K)
Gay-Lussac’s law Volume (V) and Pressure and P 1/T 1 P 2/T 2
amount (n) temperature (K)
Avogadro’s law Pressure (P) and Volume and amount V 1/n 1 V 2/n 2
temperature (T)
Don’t Forget!
It is possible to combine Avogadro’s law and the combined gas law to produce
the ideal gas equation, which incorporates the pressure, volume, temperature,
and amount relationships of a gas. The ideal gas equation has the form of
PV nRT
The terms in this equation are:
P pressure of the gas in units such as atm, torr, mm Hg, Pa.
V volume of the gas in units such as L, mL.
n number of moles of gas
T Kelvin temperature
R ideal gas constant: 0.0821 Latm/Kmol (for most problems)
The value for R is 0.0821 Latm/Kmol if the volume is expressed in liters, the
pressure in atmospheres, and the temperature in Kelvin (naturally). You could
calculate another ideal gas constant based upon different units of pressure and
volume, but the simplest thing to do is to use the 0.0821 and convert the given
volume to liters and the pressure to atm. (The temperature must be in Kelvin
in any case.)
The temperatures must be expressed in Kelvin.