ABSTRACT
The first quantitative data regarding the behavior of gases were reported by Robert Boyle in 1662. He showed that at any given temperature, the product of the pressure
P
exerted by a gas and its molar volume
v
is constant. In 1787, Jacques Charles observed that this constant is a function of temperature. Thus, the equation of state for one mole of a gas was determined to be
Pv = f
(
t
) (2.2)
It was found that
f
(
t
) was approximately linear:
f
(
t
) =
a
+
bt
. The constants
a
and
b
were estimated from experimental data. In units of liters per mole and atmospheres, an expression for
f
(
t
) was determined:
f(t)
= 22.4140 + 0.082057
t
= 0.082057 (273.16 +
t
) (2.3)
where
t
is the temperature in degree Celsius (or Centigrade). This expression can be rewritten if a new temperature scale is adapted such that
T
= 273.16 +
t
°
C. We then have, for one mole of a gas,
Pv = RT
(2.4)
where
T
is the absolute temperature and
R
is the universal gas constant whose numerical value depends on the choice of units. Table 2.1 gives the values of
R
in different sets of units.
