1. The Combined Gas Law
When measured at STP, a quantity of gas has a volume of 500 dm3. What volume will it occupy at 0 oC and 93.3 kPa?
(101.3 kPa) x (500 dm3) = (93.3 kPa) x (V2)
273 K
273 K
(101.3) x (500) = (93.3) x (V2)
P1 = kPa
T1 = 273 K
V1 = 500 dm3
P2 = kPa
T2 = 0 oC = 273 K
V2 = X dm3
V2 = dm3

2. Gay-Lussac’s Law
The pressure and absolute temperature (K) of a gas are directly related
at constant mass & volume
Temperature (K)
Pressure
(torr)
P/T
(torr/K)
248
691.6
2.79
273
760.0
2.78
298
828.4
373
1,041.2 P T
Joseph Louis Gay-Lussac ( , France) His experiments led him to propose in 1808 the Law of Combining Volumes, which states that the volume of gases involved in a chemical reaction are in a small whole number ratio.
Courtesy Christy Johannesson

3. Gay-Lussac’s Law
The pressure and absolute temperature (K) of a gas are directly related
at constant mass & volume P T
Courtesy Christy Johannesson

4. V T PV T P T PV = k P1V1 T1 = P2V2 T2 P1V1T2 = P2V2T1
Combined Gas Law V T PV T P T PV
= k
(COMBINED GAS LAW)
(Gay-Lussac’s LAW)
(CHARLES’ LAW)
(BOYLE’S LAW)
P1V1 T1 =
P2V2 T2
P1V1T2 = P2V2T1
Courtesy Christy Johannesson

5. Gas Law Calculations V PV = k T = k PV = nRT PV T = k Boyle’s Law
Charles’ Law V T
= k
P and V
change
n, R, T are
constant
Ideal
Gas Law
PV = nRT
T and V
change
P, n, R are
constant
Gas Law Calculations
P, V, and T change
n and R are constant
Combined
Gas Law PV T
= k