\
1—8.
BROWNIAN
9
_
Avogadro’s number (N) has been determined by kinetic“ theory
methods which chiey involve the viscosity of a gas. The rough
values so obtained lie between 2 X 1023 and 20 X 1023. N has
‘
also been obtained by Other methods Such as those described in
the remaining sections of this chapter.
From the product Ne, which is known with accuracy, and a
separate measurement of N or 6, the remaining quantity may be
calculated.
If @ is taken as 4.770 X 10“10 e.s.u., then
‘
N =. 6.06
1023 (i0.006).
1—8.
Brownian Movements.—When examined under a high…
power microscope, small particles suspended in a uid, such as
smoke particles in air, for example, are found to be moving rapidly
in a random fashion.
These movements were discovered by
Robert Brown in 1827.
The particles are composed of clusters of
atoms or molecules and their motion, which is one of the best evi—
dences of the Vibrations taking place in gases, is due to an unbal—
anced bombardment of the visible particle by the many invisible
molecules of the uid.
Taken over a suiciently long time inter—
Val, the number of gas molecules striking one side of the particle
would equal the number striking the opposite side, but during a
»
short
the chance bombardment is sometimes greater -
‘
on one side than on the other.“ Hence,
particle is knocked back
and forth ina tortuous path. This motion is always present; it is
;
”
the same Éfor various-particles of appropriate Size but of different
_
_
nature, “and.“ it
outside vibrations or currents
…
Due-tdBrpwian
particles in a suitable sus—
_
'
pen5mnmaybefoundsupportedaga1nst
the force“ ‘Ofgravity. Air
Particlesarepreventedfrom
the ,e’arth’s surface because
ofthecounterbalancmg forcedue to,
the
1—8.
BROWNIAN
9
_
Avogadro’s number (N) has been determined by kinetic“ theory
methods which chiey involve the viscosity of a gas. The rough
values so obtained lie between 2 X 1023 and 20 X 1023. N has
‘
also been obtained by Other methods Such as those described in
the remaining sections of this chapter.
From the product Ne, which is known with accuracy, and a
separate measurement of N or 6, the remaining quantity may be
calculated.
If @ is taken as 4.770 X 10“10 e.s.u., then
‘
N =. 6.06
1023 (i0.006).
1—8.
Brownian Movements.—When examined under a high…
power microscope, small particles suspended in a uid, such as
smoke particles in air, for example, are found to be moving rapidly
in a random fashion.
These movements were discovered by
Robert Brown in 1827.
The particles are composed of clusters of
atoms or molecules and their motion, which is one of the best evi—
dences of the Vibrations taking place in gases, is due to an unbal—
anced bombardment of the visible particle by the many invisible
molecules of the uid.
Taken over a suiciently long time inter—
Val, the number of gas molecules striking one side of the particle
would equal the number striking the opposite side, but during a
»
short
the chance bombardment is sometimes greater -
‘
on one side than on the other.“ Hence,
particle is knocked back
and forth ina tortuous path. This motion is always present; it is
;
”
the same Éfor various-particles of appropriate Size but of different
_
_
nature, “and.“ it
outside vibrations or currents
…
Due-tdBrpwian
particles in a suitable sus—
_
'
pen5mnmaybefoundsupportedaga1nst
the force“ ‘Ofgravity. Air
Particlesarepreventedfrom
the ,e’arth’s surface because
ofthecounterbalancmg forcedue to,
the