Transcript Chapter_11.1

Chapter 11:
States of
Matter and
Intermolecul
ar Forces
Section 11.1: pg. 376-384;
S.O.L. Ch 3d, 5 d,f
States of Matter
 The
states of matter are solid, liquid, gas
and sometimes plasma (which is not a
naturally occurring state)
It’s just a phase!
A
phase is a uniform collection of
particles.
 Some things can exist in two phases
(milkshakes, slushies, etc.)
 Dynamic equilibrium is a state of a
compound where the particles move
between 2 different states.
Phase Diagrams

A phase diagram shows the state of a
compound with temperature and
pressure.

The diagram shows the state of matter at a
given temperature and pressure.
The Phase Diagram
Boiling and Melting
 When
you consider standard atmospheric pressure
(1 atm), the point where the phase lines intersect
are the melting and boiling points, respectively.


Melting point: the temperature and pressure where a
solid becomes a liquid. (solid and liquid are in
equilibrium)
Boiling point: the temperature and pressure where a
liquid becomes a gas. (liquid and gas are in
equilibrium)
Temperature or Pressure
Change
 You
can add energy in the form of heat
to raise the average kinetic energy of a
substance, OR you can increase the
pressure.
Definitions
 Triple
point: the temperature and
pressure at which all three states of matter
exist at equilibrium.
 Critical point: the temperature and
pressure where gas and liquid become
identical.

Above this point the substance is said to be
a supercritical fluid
Vapor Pressure
 Vapor
pressure is the pressure produced
by a liquid or a solid when it is in dynamic
equilibrium with its gas phase and is
measured in mmHg or kPa.
 As temperature increases, vapor pressure
increases and exerts pressure on the walls
of the container.
Drawing a phase diagram
 To
plot the phase diagram, you will need
the



Triple point
Critical point
Vapor Pressure at 1 atm
Draw this
 The
triple point of SO2 is -73C and 0.17
kPa. The critical point is 158C and 7,870
kPa. The bp is -10C. The solid form is more
dense than the liquid form.
Phase Diagram
7870 kPa
101.3 kPa
0.17 kPa
-73C
-10C
158C
Answer these
 What
state is SO2 in at 200kPa and -100C?
 What state at 1 kPa and 80C?
 If you increase temp at 101.3 kPa from 20C to 20C, what happens?
 If you increase pressure at -11C from 150
kPa to 300 kPa, what happens?
Forces of Physical Properties



Cohesion is an attraction for particles
that a liquid has.
Adhesion is an attractive force for
particles of solid surfaces
Capillary action is the motion of a
liquid up a small surface and is
accomplished by adhesion of liquid
molecules to the surface of the glass
as well as cohesion between the liquid
molecules.
Surface Tension

Surface tension is the force that acts of
the surface of a liquid and tends to
minimize the area of the surface. Why?



1st of all, cohesive forces bring the molecules of
a liquid together so that they stay in contact;
2nd, under the surface of the liquid, these
cohesive forces are pulling equally in all
directions;
3rd, only on the surface, the molecules are being
pulled sideways and downward creating
surface tension.
The Energy of Tension



It takes energy to increase the surface
area of a liquid because this energy must
oppose the net forces pulling the
molecules; conversely, a liquid decrease
energy as the surface area decreases.
This tendency toward decreasing the
surface area is called surface tension.
A high surface tension means that a lot of
energy is needed to break the surface.
Application of Surface Tension


When you add the detergent to a
load of laundry, the soap decreases
the surface tension of the stain on your
clothing by disrupting hydrogen
bonds; therefore the dirt can be
carried away by the water!!!
Although, it also takes effort to load
the washing machine!
How do we have states?
The determining factor as to whether a molecular
substance is a solid, liquid or gas at room temperature is
its intermolecular forces.
Intermolecular forces - forces of attraction that exist
between molecules. (More to come!)
Gases are Special

Gases do not have the same type of
intermolecular forces, because they are
farther apart and the attractive forces are
minimized. That is why a gas will fill the
space available.
Condensed States of Matter
Liquids and Solids
Kinetic-molecular theory for gases establishes that
gas particles have significant kinetic energy and
little attractive forces between them and therefore
act independently of one another.
According to kinetic-molecular theory, the state of a
substance at room temperature depends on the
strength of attraction between the particles.
Changes in State
A
phase change is the conversion of a
substance from one of the three physical
states of matter to another.
A
phase change always involves a
change in energy.
Name that State Change
 condensation
liquid
 deposition
- release energy to convert gas to
- release energy to covert gas to solid
 freezing
- release energy to convert liquid to solid
 melting
- absorb energy to convert solid to liquid
 sublimation
- absorb energy to convert solid to gas
 vaporization
gas
- absorb energy to convert liquid to
The Water Cycle
Endothermic
Exothermic
Gas
Liquid
Solid
Homework
 Read
Chapter 11.1
 Answer Section Review Questions