States of Matter

1
States of Matter

• Liquids

2
States of Matter

• Objectives
• Describe the motion of particles in liquids and
  the properties of liquids according to the
  kinetic-molecular theory
• Discuss the process by which liquids can change
  into a gas and define vaporization
• Discuss the process by which liquids can change
  into a solid and define freezing

3
States of Matter

• Properties of Liquids and the Kinetic-Molecular
  Theory
• A liquid can be described as a form of matter
  that has a definite volume and takes the shape of
  its container
• The attractive forces between particles in a
  liquid are more effective than those between
  particles in a gas
• This attraction between liquid particles is
  caused by the intermolecular forces
• dipole-dipole forces
• London dispersion forces
• hydrogen bonding

4
States of Matter

• Properties of Liquids and the Kinetic-Molecular
  Theory
• The particles in a liquid are not bound together
  in fixed positions. Instead, they move about
  constantly
• A fluid is a substance that can flow and
  therefore take the shape of its container

5
States of Matter

• Properties of Liquids and the Kinetic-Molecular
  Theory
• Relatively High Density
• At normal atmospheric pressure, most substances
  are hundreds of times denser in a liquid state
  than in a gaseous state

6
States of Matter

• Properties of Liquids and the Kinetic-Molecular
  Theory
• Relative Incompressibility
• Liquids are much less compressible than gases
  because liquid particles are more closely packed
  together

7
States of Matter

• Properties of Liquids and the Kinetic-Molecular
  Theory
• 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
• Diffusion is much slower in liquids than in gases
  because 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

8
States of Matter

• Properties of Liquids and the Kinetic-Molecular
  Theory
• Surface Tension
• A property common to all liquids is surface
  tension, a force that tends to pull adjacent
  parts of a liquids 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
• The molecules at the surface of the water can
  form hydrogen bonds with the other water, but not
  with the molecules in the air above them

9
States of Matter

• Properties of Liquids and the Kinetic-Molecular
  Theory
• Surface Tension
• 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 and against
  the pull of gravity
• The same process is responsible for the concave
  liquid surface, called a meniscus, that forms in
  a test tube or graduated cylinder

10
States of Matter

• Properties of Liquids and the Kinetic-Molecular
  Theory
• 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 non-boiling liquid
  and enter the gas state
• Boiling is the change of a liquid to bubbles of
  vapor that appear throughout the liquid
• Evaporation occurs because the particles of a
  liquid have different kinetic energies

11
States of Matter

• Properties of Liquids and the Kinetic-Molecular
  Theory
• Formation of Solids
• When a liquid is cooled, the average energy of
  its particles decreases
• The physical change of a liquid to a solid by
  removal of energy as heat is called freezing or
  solidification