Properties of Liquids
Properties of Liquids
• Definite volume
• Indefinite shape
• Particles are close together, but can move
a little bit. Liquids can flow.
• Density of liquids is much greater than
gases. Ex: DH2Ol is 1250X greater than
DH2Og at 25C.
• Liquids can be compressed but change in
volume is very slight & requires enormous
pressure.
Viscosity
• Liquids exhibit viscosity.
• Viscosity = resistance to flow.
• Viscosity depends on strength of
intermolecular forces, sizes & shapes of
molecules, and temperature.
• The stronger the intermolecular forces, the
higher the viscosity.
• As temperature , viscosity .
• As temperature , viscosity .
Oil in an engine
prevents direct metal
to metal contact.
Need a thin film of oil
on bearing surfaces
to prevent flaking of
metal.
If the oil is too thick, it
won’t circulate at low
temperatures.
If the oil is too thin, it
will lose film strength
at high temperatures.
Where does the
marble drop
fastest? water
Slowest?
glycerol
Viscosity & Petroleum Drilling
Surface Tension
• Particles at the surface of a liquid exist in an
unbalanced environment. No attraction from
above to balance attractions from below.
• Net attractive force pulling down.
• Surface seeks smallest possible area.
Surface Tension
• Surface Tension = energy required to
increase the surface area by a given
amount. = measure of inward pull.
• Strong intermolecular attractions  High
surface tension.
Surfactants
• Compounds that lower the surface tension
of water
• Disrupt hydrogen bonds between H2O
molecules.
• See video
Capillary Action
• Water forms a concave meniscus in a
glass tube.
• Attractive forces between water and glass
> attractive forces between the water
molecules.
• Upward movement of a liquid in a narrow
tube = capillary action.
Force(H2O-glass) 
Force(H2O- H2O)
Force(Hg-glass) 
Force(Hg-Hg)