Lecture 3 / PURE SUBSTANCES Flashcards
is
a substance that has
a fixed chemical
composition
throughout.
E.g. water, nitrogen,
helium, and carbon
dioxide
Pure substances
_________ molecules are
arranged in a ______ which
is an ordered array of points
describing the arrangement
crystal-forming particles.
SOLID ; LATTICE
_______ is a __________
state since it is not ready to
vaporize.
STATE 1 ; a compressed liquid
It is called a __________
– a liquid that is about to
vaporize.
STATE 2 ; saturated liquid
Once boiling starts, the
temperature stops rising until
the liquid is completely
vaporized.
That is, the temperature will
remain constant during the
entire phase-change process
if the pressure is held
constant.
STATE 3
Any heat loss from this vapor
will cause some of the vapor
to condense (phase change
from vapor to liquid).
A vapor that is about to
condense is called a
____________
STATE 4 ; saturated vapor
A vapor that is not about to
condense is called a
___________________
Therefore, water at ________ is
__________________
STATE 5 ; superheated vapor
the amount of energy
absorbed or released during a
phase-change process
Latent heat
the amount of
energy absorbed during melting equal to
the amount of energy released during
freezing
Latent Heat of Fusion
the
amount of energy absorbed during
vaporization equal to the energy
released during condensation
Latent Heat of Vaporization
the quantity of hfg is called
Latent Heat of Vaporization
the point at which the saturated
liquid and saturated vapor states are identical
Critical Point
The ____________ separates the solid and vapor
regions;
sublimation line
The ________________ separates the liquid and vapor
regions;
vaporization line
And the __________ line separates the solid and
liquid regions.
melting or fusion
The
aforementioned
three lines meet
at the ___________, where all
three phases
coexist in
equilibrium.
triple
point,
the temperature at which a
pure substance changes
phase at a given pressure
saturation temperature, Tsat
the pressure at which a pure
substance changes phase at
a given temperature
saturation pressure, Psat
A plot of Psat versus Tsat is
called a
liquid–vapor
saturation curve.
All the states that
involve both phases
in equilibrium are
located under the
dome, called the
saturated
liquid–vapor mixture
region,
A thermodynamic property
designed simplify our
reference to the combined
values of Pv and u terms.
Enthapy, h
To analyze this mixture
properly, we need to know
the proportions of the liquid
and vapor phases in the
mixture.
This is done by defining a
new property
called the___________
quality x
the ratio of the
mass of vapor to the total
mass of the mixture:
Quality, x
Any equation that
relates the pressure,
temperature, and
specific volume of a
substance is called an ______________
equation of state
The simplest and
best-known equation of
state for substances in
the gas phase is the
ideal-gas equation of
state.
