Download Topic 7 Section 2 Liquids and solids

BELL RINGER
What happens to gas particles
when a gas is heated?
• Average Kinetic energy increases
(speed)
• More collisions between particles
and
between
particles
and
container.
Topic 7
The Kinetic-Molecular Theory
Table of Contents
Section 1 The Kinetic-Molecular Theory of Matter
Section 2 Liquids and Solids
Section 3 Changes of State
Section 4 Water
Topic 7
Section 2 Liquids and solids
• How are you able to tell that a container is filled
with a liquid?
• Liquids have definite volume but take the shape
of their container.
• How is this different from gases?
• Gases do not have a fixed shape or a fixed
volume.
Topic 7
Section 2 Liquids and solids
Properties of Liquids and the KMT
• The attractive forces between particles in a liquid
are more effective than those between particles
in a gas.
• This attraction is caused by the intermolecular
forces:
• dipole-dipole forces
• London dispersion forces
• hydrogen bonding
Topic 7
Section 2 Liquids and solids
Properties of Liquids and the KMT
• The particles in a liquid move about constantly.
• A fluid is a substance that can flow and therefore
take the shape of its container.
1.Relatively High Density
• At normal atmospheric pressure, most substances
are hundreds of times denser in a liquid state than in
a gaseous state.
Topic 7
Section 2 Liquids and solids
Properties of Liquids and the KMT
2. Relative Incompressibility
•
Liquids are much less compressible than gases
because liquid particles are more closely packed
together.
3. Ability to Diffuse
•
Any liquid gradually diffuses throughout any other
liquid in which it can dissolve.
The constant, random motion of particles causes
diffusion in liquids.
Topic 7
Section 2 Liquids and solids
Properties of Liquids and the KMT
3. Ability to Diffuse
•Diffusion is much slower in liquids than in
gases. Why?
• Liquid particles are closer together.
• The attractive forces between the particles of a
liquid slow their movement.
•As the temperature of a liquid is increased,
diffusion occurs more rapidly.
Topic 7
Section 2 Liquids and solids
Properties of Liquids and the KMT
Surface Tension
• A force that tends to pull
adjacent parts of a liquid’s
surface
together,
thereby
decreasing surface area to the
smallest possible size.
• The higher the force of
attraction between the particles
of a liquid, the higher the
surface tension.
Topic 7
Section 2 Liquids and solids
Properties of Liquids and the KMT
•Capillary action is the
attraction of the surface of
a liquid to the surface of a
solid.
•This attraction tends to
pull the liquid molecules
upward along the surface.
•The same process is responsible for the concave
liquid surface, called a meniscus, that forms in a test
tube or graduated cylinder.
Topic 7
Section 2 Liquids and solids
Properties of Liquids and the KMT
Evaporation and Boiling
• The process by which a liquid or solid
changes to a gas is vaporization.
• Evaporation is the process by which
particles escape from the surface of a
nonboiling liquid and enter the gas
state.
• Evaporation occurs because the
particles of a liquid have different
kinetic energies.