1.1 What is Chemistry?

http://www.ck12.org Chapter 14. The Properties of Gases

T 1 = 25 ◦C+ 273 =298 K

T 2 = 50 ◦C+ 273 =323 K

V 1 =752 mL

V 2 =?

V 1

T 1

=

V 2

T 2

V 2 =

V 1 T 2

T 1

V 2 =

(752 mL)(323 K)

298 K

V 2 =815 mL

Gay-Lussac’s Law

Gay-Lussac’s Lawdescribes the relationship between pressure and absolute temperature:
P
T=k
P 1
T 1 =

P 2

T 2

Gay-Lussac’s law says that at a constant volume, the pressure of a gas is directly proportional to its absolute
temperature. This relationship is also sometimes attributed to Guillaume Amontons (1663–1705). Although his
work predated that of Gay-Lussac by over a century, the data on which he based his ideas were considerably less
precise, due to the cruder instrumentation available at the time.

Example 14.5

The gas in an aerosol can exerts a pressure of 3.00 atm at 25°C. Directions on the can warn the user not to keep the
can in a place where the temperature exceeds 52°C. What would the gas pressure in the can be at 52°C? Before you
begin, do you think the pressure should go up, down or stay the same?

Answer:

Again, don’t forget that all temperatures must be converted to absolute temperature (Kelvin).

T 1 = 25 ◦C+ 273 =298 K

T 2 = 52 ◦C+ 273 =325 K

P 1 = 3 .00 atm

P 2 =?

P 1

T 1

=

P 2

T 2

P 2 =

P 1 T 2

T 1

P 2 =

( 3 .00 atm)(325 K)

298 K

P 2 = 3 .27 atm

Note that the pressure increases, which would be expected if the temperature were to go up.