Chapter 10 States of Matter

Section 1: The Kinetic-Molecular Theory of Matter

KMT This is based on the idea that particles of matter are always in motion. How it relates to gases: Ideal gas = a hypothetical gas that perfectly fits all the assumptions of KMT. No ideal gas actually exists; but some do come close.

5 Assumptions Gases consist of large numbers of tiny particles that are far apart relative to their size. Collisions between gas particles and between particles and container walls are elastic collisions (no net loss of total kinetic energy) Gas particles are in continuous, rapid, random motion. Thus, they have kinetic energy.

5 Assumptions Cont. There are no forces of attraction between gas particles. This is why they have no set shape The temperature of the gas depends on the average kinetic energy of the particles of the gas.

Properties of Gases No definite shape No definite volume Ability to flow (fluid) Low density Can be compressed smaller Diffusion Effusion

Real Gases A gas that does not behave completely according to the assumptions of KMT. Noble gases and non-polar diatomic gases behave most like an ideal gas, as well as gases at high temperatures and low pressures.

Section 2 & 3: Liquids and Solids

Properties of Liquids No definite shape Higher density Mostly incompressible so definite volume Diffusion Surface tension Evaporation Boiling Can form solids

Properties of Solids Definite shape Definite volume Defined melting point High density Incompressible Low rate of diffusion

Types of Solids Crystalline Solids: exist as single crystals or groups of crystals fused together. Ionic Crystals Covalent Network Crystals Metallic Crystals Covalent Molecular Crystals

Types of Solids Amorphous Solids: are not arranged in a regular pattern. Glass and Plastic

Chapter 10.4 Changes of State

Matter on earth can exist in any state—gas, liquid, or solid—and can change from one state to another.

Energy and Changes of State When a substance changes from one state to another, energy is always involved. The change will either be exothermic (releases heat) or endothermic (absorbs heat).

Changes of State Change of State Process Example Endo or Exo? SolidLiquid Melting IceWater SolidGas Sublimation Dry IceCO2 LiquidSolid Freezing WaterIce LiquidGas Vaporization WaterSteam GasSolid Deposition SteamIce GasLiquid Condensation SteamWater

Phase Diagrams Phase Diagram: a graph of pressure versus temperature that shows the conditions under which the phases of a substance exist. Tells you what state a substance will be in at a certain temperature and pressure.

Triple point: the temperature and pressure conditions at which the three phases can coexist at equilibrium Critical Point: the critical temperature and critical pressure of a substance.

Critical Temperature: the temperature above which the substance cannot exist as a liquid. Critical Pressure: the lowest pressure at which the substance can exist as a liquid.

Name that state… Temperature Pressure State 70°C 2.0 atm 100°C 0.5 atm

Name that state… Temperature Pressure State 70°C 2.0 atm 100°C 0.5 atm Liquid Gas Solid

Chapter 10.5 Water

Structure of Water Recall: Water has 2 Hydrogen and 1 Oxygen and has a bent structure. Ice forms a hexagonal pattern Look at Fig 19 on pg 350 The empty spaces result in ices low density and are why it floats.

Properties of Water Pure water is transparent, odorless, tasteless and almost colorless. Any odor or taste is caused by impurities. Water freezes and ice melts at 0°C and 1 atm. Molar enthalpy of fusion is 6.009 kJ/mol Water boils at 100°C and 1 atm. Molar enthalpy of vaporization is 40.79 kJ/mol

Going from ice to water requires energy. Going from water to ice releases energy. Going from water to steam requires energy. Going from steam to water releases energy. The amount of energy is the same, it is just either required or released.

Calculating Amount of Energy  

Calculating Amount of Energy  

Homework Pg 351 #4, 6 and practice problem #1, 2