D611_A1.2
0 (0 Likes / 0 Dislikes)
Clean and dry the apparatus.
Deliver 10 milliliters
leaders of aniline--
warning, see 7.1--
and 10 milliliters
of the dried sample, 8.1,
into the test tube fitted
with a stirrer and thermometer.
If the material is too viscous
for volumetric transfer,
weigh to the nearest 0.01
gram a quantity of the sample
corresponding to 10 milliliters
at room temperature.
Center the thermometer
in the test tube
so that the immersion mark
is at the liquid level,
making sure that the
thermometer bulb does not
touch the side of the tube.
Center the test tube
in the jacket tube.
Stir the mixture rapidly,
using a 50 millimeter--
2 inch-- stroke, avoiding the
introduction of air bubbles.
If the aniline
sample mixture is not
miscible at room
temperature, apply heat
directly to the jacket tube
so that the temperature
rises at a rate of 1
to 3 degrees Celsius--
2 to 5 degrees Fahrenheit-- per
minute by removing or reducing
the heat source until complete
miscibility is obtained.
Continue stirring
and allow the mixture
to cool at a rate of 0.5
to 1.0 degrees Celsius--
1.0 to 1.8 degrees
Fahrenheit-- per minute.
Continue cooling to a
temperature of 1 to 2 degrees
Celsius--
2.0 to 3.5 degrees Fahrenheit--
below the first appearance
of turbidity and
record as the aniline
point the temperature at
which the mixture suddenly
becomes cloudy throughout.
Note A1.1.
This temperature and
not the temperature
of separation of small
amounts of material
is the minimum equilibrium
solution temperature.
The true aniline
point is characterized
by a turbidity that is so cloudy
as to obscure the thermometer
bulb in reflected light.
If the aniline sample mixture
is completely miscible at room
temperature, substitute a
non-aqueous cooling bath
for the heating source.
Allow to cool at the
rate specified in A.1.2.2
and determine the aniline
point as described.
Repeat the observation of
aniline point temperature
by heating and cooling
repeatedly until a report
as directed in section
11 can be made.