160
Gases
Some other frequently used values of R are
R = 1.987
cal
= 8 314 x 10
7
, __
mole K
The following problems illustrate a variety of applications of Equation 1 1-3
In each case the important thing to see is how the given situation is related to the
ideal gas law Don't try to think of each problem as needing a special equation;
learn to reason from the one equation
PROBLEM:
What is the volume of one mole of any gas at room conditions (740 torr and 27°C)
r>
SOLUTION:
p
J1 mole) (62 4;^^) (300 K)
740 torr
= 25 3 liters
PROBLEM:
What will be the pressure exerted by an\ gas in a sealed vessel if its temperature is
raised to 200°C from 20°C, where its pressure is 600 torr
17
SOLUTION:
To avoid making a big production out of this problem, you need to realize that the
vessel is sealed Therefore, V and n are constant during this change, and Equation
1 1-3 can be written as
P, Pi nR
-By substituting the given conditions and solving for/
3 .,, we get
PJ±_ (600 torr)(473 K) _
^
2 ~ T, ~
(293 K)
~
y
PROBLEM:
What is the density of NH 3 gas at 67°C and 800 torr"
1