Download Chapter 13 States of Matter

Chapter 13
States of Matter
SOLIDS, LIQUIDS AND GASSES
The Kinetic Molecular Theory
Basic Assumptions
Particle Size
• Gas particles have no volume (pin point particles)
• The space between particles is extremely large
compared to the volume of the particles. Due to this
distance, there is no significant attractive or repulsive
force acting on the particles.
The Kinetic Molecular Theory
Basic Assumptions
Particle Motion
• Gas particles are in constant random motion.
• Collisions between particles are elastic (Energy can be
transferred from one particle to another during a
collision, but no energy is lost when particles collide)
Gas Pressure
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The force that a gas exerts per unit area as a result of
the simultaneous collisions of many particles
No particles = no pressure = a vacuum
The Mercury Barometer
Invented by Evangelista Torricelli
Two forces affect the height of the
mercury column
Gravity and Atmospheric Pressure
Equivalent pressure units
760 mm Hg = 101.3 kPa = 1atm = 760 torr = 14.7 psi
Kinetic Energy and Temperature
Average Kinetic Energy of particles in a substance is directly
proportional to the Kelvin temperature of a substance.
13.2 The Nature of Liquids
Particle Spacing
 Intermolecular attractions reduce the amount of space
between particles in a liquid.
Particle Motion
 Particles in a liquid have enough kinetic energy to flow
 The tendency for particles move and their attraction for
one another account for the physical properties of liquids
Vaporization vs. Evaporation
 Vaporization is the conversion of a liquid to a gas
 Evaporation is vaporization that occurs at the surface of a
liquid that is not boiling.
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Evaporation depends on the
intermolecular forces that hold the
particles in a liquid together.
If the forces are weak, then the
kinetic energy of the particles at the
surface can overcome the
intermolecular forces that hold
them together.
Adding heat will increase the rate of
evaporation of a liquid
Vapor Pressure
 Vapor pressure is a measure of the forced exerted by a
gas over a liquid.
 Vapor pressure is created in a closed system as particles
in a liquid evaporate and collide with the walls of the
container.
 There is a direct relationship between temperature and
vapor pressure.
Manometer
Boiling
 Boiling occurs at the temperature when the vapor
pressure of a liquid equals the pressure exerted by the
atmosphere.
 The boiling point of a liquid is when the liquid changes
from a liquid to a gas
 Not all substances boil at the same temperature because
of intermolecular attractions.
The Nature of Solids
 Particles are arranged in an orderly fashion with fixed
locations within a solid.
 Heat increases the kinetic energy of particles in a solid
which causes the organization of the solid to break-down
= Melting.
 The melting point of a solid is the temperature at which a
solid changes into a liquid.
The Structure of Solids
 Most solids are crystalline
 The unit cell is the smallest group of particles in a crystal
that retain the geometric shape of the crystal
 There are 7 crystal systems
Allotropes and Amorphous Solids
 Allotropes are solid substances that can exist in more
than one form in the same physical state.
Allotropes of Carbon
Amorphous Solid
 Amorphous solids lack an ordered internal structure
Heating Curve and Change of State
Endothermic Phase Changes
 Melting- solid absorbs
energy until particles have
enough speed to break
free of IM forces holding
them in place
 Vaporization-liquid
absorbs energy until
particles have enough
speed to break free of IM
forces holding them close
together
 Sublimation – Solids are
converted directly to gases
without forming a liquid
Exothermic Phase Changes
 Freezing – liquid particles
release energy and
particles become highly
organized
 Condensation-gases lose
energy and particles come
close enough together to
experience intermolecular
forces
 Deposition – Process by
which a gas turns into a
solid without the
formation of a liquid
Phase Changes
Phase Changes
Phase Diagrams
 Phase diagrams show the temperature and pressure
conditions at which a substance exists as a solid,
liquid, or gas
Triple oint