Some Properties of Solids, Liquids, and Gases Property Solid Liquid Gas Shape Volume Arrangement of Particles definite shape shape of container shape of container definite volume definite volume volume of container fixed, very close random, close random, far apart The three common phases (or states) of matter are gas, liquid, and solid 1. Gases a. Have the lowest density of the three states of matter b. Are highly compressible c. Completely fill any container in which they are placed d. Their intermolecular forces are weak e. Molecules are constantly moving independently of the other molecules present 2. Solids a. Dense b. Rigid c. Incompressible d. Intermolecular forces are strong e. Molecules locked in place 3. Liquids b. Incompressible c. Flow readily to adapt to the shape of the container d. Sum of the intermolecular forces are between those of gases and solids • The state of a given substance depends strongly on conditions
Unusual Heating/Cooling Curve (Axes switched)
Boiling- Molecules throughout the liquid have enough energy to vaporize. Happens at the boiling point temperature.
Microscopic view of a liquid near its surface Evaporation- Only the high energy molecules escape the surface in to the gas phase. Happens at temperatures below the boiling point.
Make sense of these …and rank the three types of IMFs in ascending order of strength High Boiling Point WEAK IMFs High V.P. Low V.P. STRONG IMFs Low Boiling Point
Behavior of a liquid in a closed container… Once it’s at equilibrium, the pressure of the gas above the liquid in a closed container is called… VAPOR PRESSURE!
Vapor Pressure Strong IMFs Weak IMFs measure of the tendency for liquid particles to enter gas phase at a given temp. a measure of “stickiness” of liquid particles to each other Strong IMFs more “sticky” less likely to vaporize In general: LOW v.p. not very more likely to HIGH v.p. Weak IMFs NOT all liquids have same v.p. at same temp.
Heating Curves & Phase Changes Plot of temperature change versus heat added Phase change = Transformation of a substance from one state of matter to another During a phase change, adding heat does NOT change the temperature!!
Gas – e.g. steam Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31
LIQUID – e.g. water some writing from Kotz (PowerPoint online) Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31
SOLID – e.g. ice Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.