Properties of Liquids Properties of Liquids Definite volume

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: DH 2 O(l) is 1250 x greater than DH 2 O(g) at 25 C (room temp) • 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

• 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 marble drop fastest? water Slowest? 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

Surfactants • Compounds that lower surface tension of H 2 O • Disrupt hydrogen bonds between H 2 O molecules • See video

Capillary Action • water forms concave meniscus in glass tube • attractive forces between water and glass greater than attractive forces between water molecules • upward movement of liquid in narrow tube = capillary action

Force(H 2 O-glass) Force(H 2 O- H 2 O) Force(Hg-glass) Force(Hg-Hg) CONVEX CONCAVE meniscus