Topic: Properties of Liquids
Do Now:
Properties of Liquids
• Definite volume
• Indefinite shape
• Particles close together, but can move little bit
– Liquids can flow
• Density liquids much greater than gases
– Ex: DH2O(l) is 1250x greater than
DH2O(g) at 25C (room temp)
• Liquids can be compressed but change in
volume very slight & requires enormous
pressure
• Viscosity
• Surface Tensions
– Today we will learn about these physical
properties:
Viscosity
• Viscosity = resistance to flow
• Viscosity depends on:
– strength of IMF (force between
molecules)
– sizes & shapes of molecules
– & temperature
• stronger the IMF, the higher the viscosity
– as temperature , viscosity 
– as temperature , viscosity 
Where does the
marble drop
fastest?
water
Slowest?
glycerol
See demo (slide 10 of 13)
•engine oil prevents direct
metal to metal contact
•thin film oil on surfaces
prevents metal from flaking
•if oil too thick, won’t
circulate at low temps
•if oil too thin, will lose
film strength at high
temps
Surface Tension
• Particles at surface of liquid exist in
unbalanced environment
– No attraction from above to balance attractions
from below
• Surface seeks
smallest possible area
• Net attractive force
pulling down
DEMO
Surface Tension
• Surface Tension = E required to ↑surface area
= measure of inward pull
• Strong intermolecular attractions 
High surface tension
Washing with cold water
The major reason for using hot water for
washing is that its surface tension is lower and it
is a better wetting agent. But if the detergent
lowers the surface tension, the heating may be
unnecessary.
• Increasing heat lowers temperature
• Compounds that lower surface tension of H2O
are called SURFACTATS
• Disrupt hydrogen bonds between H2O
molecules
• See video
Don't touch the tent!
Common tent materials are somewhat
rainproof in that the surface tension of
water will bridge the pores in the finely
woven material. But if you touch the tent
material with your finger, you break the
surface tension and the rain will drip
through.
Soaps and detergents
help the cleaning of clothes by
lowering the surface tension of the
water so that it more readily soaks
into pores and soiled areas.
Capillary Action
• Water forms concave
meniscus in glass tube
• Attractive forces between
water and glass is greater than
attractive forces between
water molecules
• Upward movement of liquid in
narrow tube = capillary action
Force(H2O-glass) 
Force(H2O- H2O)
Force(Hg-glass) 
Force(Hg-Hg)
Force(Hgglass
CONVEX
CONCAVE
meniscus
meniscus