GayLussacs Law

1
Gay-Lussacs Law
2
Joseph Gay-Lussac
(1778-1850)

• Studied the relationship between pressure and
  temperature in gases
• Ascended to heights of over 4 miles in balloons
  to collect air samples
• Most well-known for his studies of combining
  volumes of gases

3
Pressure vs. Temperature

• As the temperature of a gas increases, if its
  volume remains constant, the pressure also
  increases

• Temperature must be measured in Kelvin

• Number of moles and volume are constant

4
P1/TK1 P2/TK2

• P1 initial pressure

• TK1 initial Kelvin temperature

• P2 final pressure

• TK2 final Kelvin temperature

• Three of the four must be known (or knowable)

• Any consistent units for P are acceptable

• Temperature must be in Kelvin.

• V and n must be constant.

• The identity of the gas is irrelevant.

5
2.70 atm
Example 1 An aerosol can is filled with gases to
a pressure of 2.70 atm at 22.0ºC. This maximum
safe pressure for the can is 5.0 atm. Will it
expode when heated in a fire to a temperature of
265ºC.
22.0ºC
Will it explode? means Will the pressure
exceed 5 atm?
265.0ºC
1. P1 2.70 L
3. P2 ?
2. T1 22.0ºC
4. T2 265.0ºC
295.0 K
538 K
Remember, temperatures must be expressed in
Kelvin units. (TK TC 273)
Substituting into the equation
P1/T1 P2/T2
P2
(2.70 atm)

(295.0 K)
(538 K)
P2
(0.00915)
(538 K)
P2 4.92 atm
(0.00915)(538 K) P2
Because the pressure does not exceed 5 atm, the
can would not explode.
6
2.70 atm
Example 2 An aerosol can is filled with gases to
a pressure of 2.70 atm at 22.0ºC. This maximum
safe pressure for the can is 5000. torr. At what
temperature would the can explode?
5000. torr
22.0ºC
At what temperature?
1. P1 2.70 atm
3. P2 5000. torr
x 760 2050 torr
2. T1 22.0ºC
4. T2 ?
295.0 K
Remember, temperatures must be expressed in
Kelvin units. (TK TC 273)
The pressure units must be the same. In this
case, we will convert atm to torr (atm x 760
torr)
Substituting into the equation
P1/T1 P2/T2
5000. torr
(2050 torr)

(295.0 K)
T2
(2050) T2
(5000.)(295.0)
(2050)
(2050)
T2 719.5 K 446.4ºC
The can will explode when the temperature exceeds
446.4ºC.
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For homework, print out and complete
Gay-Lussacs Law Worksheet Practice Problems
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