Chemistry Reference
In-Depth Information
P
1
V
1
T
1
P
2
V
2
T
2
(1.00 atm) (17.3 mL)
(273 K)
(0.892
1
atm) (10.9 mL)
T
2
(0.0633
7
)
T
2
9.72
4
K
T
2
153 K
The problem requires the answer in Celsius:
153 K
273
120°C
Practice Problem 12.9
Calculate the volume at standard temperature
and pressure of a sample of gas that has a volume of 49.7 mL at
52°C
and
811 torr.
Snapshot Review
❒
If both temperature and pressure of a given sample of gas change, the
combined gas law can be used to calculate the volume.
ChemSkill Builder
7.1, 7.2
A. Calculate the new volume after a 2.00-L sample of gas at 1.50 atm and
is changed to
127°C
27°C
at 3.50 atm.
12.5
The Ideal Gas Law
The gas laws presented in the preceding sections apply to a given sample of
gas. The combined gas law, written in the form
PV
T
k
may be rewritten as
PV
T
nR
where
n
represents the number of moles of gas molecules in the sample and
R
is another constant, valid for
any
sample of
any
gas. For the purpose of the gas
laws, an atom of a monatomic gas, such as neon, is considered a molecule.
EXAMPLE 12.10
Consider a given sample of gas with pressure
P
and volume
V
at temperature
T
(Figure 12.6). A second sample of the same gas under the same conditions
would have the same value of
k,
the constant in the combined gas law. What
combined gas law constant would apply to the two samples of gas together?
