DENSITY
LIQUID
TEMP. - As temp
increases as density decreases (Inversely)
For example at
low temp. the bitumen is thick, more dense. As temp. increases, the density of
bitumen is lower.
PRESSURE - As
pressure increases as density increases (Directly)
At the core of earth
when the pressure is the high, the core liquids is thick, more dense.
GASES
TEMP. - As temp
increases the density decreases (Indirectly)
The gas at the
surface of heath gets hotter and its moves up, less dense. Cold gases come down
on the earth.
PRESSURE - As
pressure increases the density increases (Directly)
For example at
low pressures the gas are moving at lower speeds, low inter-molecular
forces. As temp. increases, the gas molecules more around faster, more
dense.
PV =nRT
VISCOSITY
While liquids
get runnier as they get hotter, gases get thicker. (If one can imagine a
"thick" gas.)
LIQUID
TEMP. - As temp
increases the viscosity decreases (Inversely)
Honey and
syrups can be made to flow more readily when heated. Engine oil and hydraulic
fluids thicken appreciably on cold days and significantly affect the
performance of cars and other machinery during the winter months. the
viscosity of a simple liquid decreases
with increasing temperature (and vice versa). As temperature increases, the
average speed of the molecules in a liquid increases and the amount of time
they spend "in contact" with their nearest neighbors decreases.
Thus, as temperature increases, the average intermolecular forces
decrease.
PRESSURE - At
very high pressures, as pressure increases the viscosity increases
(Directly)
Viscosity is
normally independent of pressure, but liquids under extreme pressure often
experience an increase in viscosity. Since liquids are normally incompressible,
an increase in pressure doesn't really bring the molecules significantly closer
together.
GASES
TEMP. - As temp
increases the viscosity increases (Directly)
The viscosity
of gases increases as temperature increases and is approximately proportional
to the square root of temperature. This is due to the increase in the frequency
of intermolecular collisions at higher temperatures. Since most of the time the
molecules in a gas are flying freely through the void, anything that increases
the number of times one molecule is in contact with another will decrease the
ability of the molecules as a whole to engage in the coordinated movement. The
more these molecules collide with one another, the more disorganized their
motion becomes.
PRESSURE - Independent
The
viscosity of an ideal gas is independent of pressure, and this is almost true
for real gases. In gases, Viscosity arises mainly because of the transfer and
exchange of molecular momentum. How come pressure doesn't affect the viscosity
then?
Double
the pressure, and you double the number of molecules arriving at a surface, but
on average they will only have come from half as far away, and the effects
cancel out
