Presentation on theme: "States and state change"— Presentation transcript:
1 States and state change Chapter 11 sec 1States and state change
2 States of MatterThe fundamental difference between states of matter is the distance between particles.
3 States of MatterGases – fill container, random rapid motion, never coming to rest or clumping togetherMotion is mainly translationalLiquids – fixed volume, flow and assume shape of container, only slightly compressible, stronger forces hold molecules togetherMotion is mainly translationalEOSSolids – fixed volume, definite shape, generally less compressible than liquids, forces hold particles in a fixed shapeMotion is mainly vibrational
4 Solid particles have fixed position Crystalline form: they can be very hard and brittle or they can be very soft.
5 Liquid particles can move easily past one another Liquid flow to take the shape of the lower part of a container.A meniscus is the interface between a liquid and the air above itEOSCapillary action results from intermolecular interactions
6 Surface TensionSurface tension (g) is the amount of work required to extend a liquid surface and is usually expressed in unit of J m–2Adhesive forces are intermolecular forces between unlike moleculesCohesive forces are intermolecular forces between like moleculesEOS
7 Vaporization and Condensation Vaporization is the conversionof a liquid to a gas.EOSCondensation is the change of a gas to a liquid.The boiling point of a liquid is the temperature at which its vapor pressure becomes equal to the external pressure
8 Phase Changes Involving Solids The conversion of a solid to a liquid is called melting, or fusion, and the temperature at which a solid melts is its melting pointSublimation is the process of a molecule’s passing directly from the solid to the vapor state
9 Phase DiagramsA phase diagram is a graphical representation of the temperature and pressure conditions under which a substance exists as a solid, liquid, gas, or some combination of these in equilibriumEOScritical pointfusion curvevapor pressure curvesublimation curvetriple point
10 PracticeA sample of water has a fixed volume and shape. What state is it in?What property of a liquid enable you to pour a liquid into a cup until the top of the liquid is slightly higher than the top of the cup?During what process does a liquid change to solid?solidSurface tensionfreezing