Presentation on theme: "States and state change"— Presentation transcript:
1States and state change Chapter 11 sec 1States and state change
2States of MatterThe fundamental difference between states of matter is the distance between particles.
3States 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
4Solid particles have fixed position Crystalline form: they can be very hard and brittle or they can be very soft.
5Liquid 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
6Surface 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
7Vaporization 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
8Phase 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
9Phase 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
10PracticeA 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