Properties of Liquids

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 25C

• Liquids can be compressed but change in volume very slight & requires enormous pressure

Viscosity

• Liquids exhibit viscosity

• Viscosity = resistance to flow

• Viscosity depends on: – strength of IMF– sizes & shapes of molecules– & temperature

• stronger the IMF, the higher the viscosity– As temperature , viscosity – As temperature , viscosity

•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

Where does the Where does the marble drop fastest?marble drop fastest?

Slowest?Slowest?

water

glycerol

Viscosity & Petroleum Drilling

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

Surface Tension

• Surface Tension = E required to ↑surface area = measure of inward pull

• Strong intermolecular attractions High surface tension

http://www.esb.utexas.edu/mabrybio211/chapter03/08-Surface-Tension-Water.jpg

http://images.google.com/imgres?imgurl=http://www.public.asu.edu/~jpbirk/CHM-113_BLB/Chpt11/img032.jpg&imgrefurl=http://www.public.asu.edu/~jpbirk/CHM-113_BLB/Chpt11/sld032.htm&h=360&w=480&sz=144&tbnid=x3lFHb880JsJ:&tbnh=94&tbnw=125&start=295&prev=/images

http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter10/Text_Images/FG10_08.JPG

Surfactants

• Compounds that lower surface tension of H2O

• Disrupt hydrogen bonds between H2O molecules

• See video

http://www.weeds.iastate.edu/reference/visuals/additives/img007.gif

Capillary Action

• Water forms concave meniscus in glass tube

• Attractive forces between water and glass > attractive forces between water molecules

• Upward movement of liquid in narrow tube = capillary action

http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH11/FG11_30.JPG

Force(Hg-glass) Force(Hg-Hg)

Force(H2O-glass) Force(H2O- H2O)

CONVEX CONCAVE