Chapter 10 States of Matter

Section 1: The Kinetic-Molecular Theory of Matter

Standard 4.b.  Students know the random motion of molecules explains the diffusion of gases.  We will list the five assumptions of the kinetic- molecular theory of gases and describe the properties of gases. Objectives

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 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. KE = ½mv 2

Standard 4.b.  Students know the random motion of molecules explains the diffusion of gases.  We will list the five assumptions of the kinetic- molecular theory of gases and describe the properties of gases. Objectives

Properties of Gases  No definite shape  No definite volume  Ability to flow (fluid)  Low density  Can be compressed  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.

Standard 4.b.  Students know the random motion of molecules explains the diffusion of gases.  We will list the five assumptions of the kinetic- molecular theory of gases and describe the properties of gases. Objectives

Homework  Page 332 #2, 5, 6  Page 353 #1, 4

Section 2 & 3: Liquids and Solids

Standard 4.a.  Students know the random motion of molecules and their collisions with a surface create the observable pressure on that surface.  We will describe the properties of liquids and discuss the processes of how liquids change.  We will describe the properties of solids and distinguish between the two types of solids. Objectives

Properties of Liquids  No definite shape  Definite volume  Higher density  Diffusion  Surface tension  Evaporation  Boiling  Freezing

How Liquids Change  Evaporation and Boiling Vaporization: when a liquid changes to a gas. Evaporation: gas forming from a nonboiling liquid. Boiling: the change of a liquid to bubbles of vapor that appear throughout the liquid.

Freezing  When liquids cool, their average kinetic energy decreases, and the attractive forces pull the particles into an orderly arrangement.  Freezing: the physical change of a liquid to a solid by removal of energy as heat.

Standard 4.a.  Students know the random motion of molecules and their collisions with a surface create the observable pressure on that surface.  We will describe the properties of liquids and discuss the processes of how liquids change.  We will describe the properties of solids and distinguish between the two types of solids. Objectives

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 Plastic

Standard 4.a.  Students know the random motion of molecules and their collisions with a surface create the observable pressure on that surface.  We will describe the properties of liquids and discuss the processes of how liquids change.  We will describe the properties of solids and distinguish between the two types of solids. Objectives

Homework  pg 336 #3-6  pg 341 #2-3

Chapter 10.4 Changes of State

Standard 7.c.  Students know energy is released when a material condenses or freezes & is absorbed when a material evaporates or melts.  We will describe the processes that occur to cause a change of state.  We will interpret phase diagrams. Objectives

 Phase: any part of a system that has uniform composition and properties.  Equilibrium: when two opposing changes occur at equal rates in a closed system. Example: Boiling water on the stove with a lid on. Water is turning into a gas, and then condensing on the lid and falling back into the pot as a liquid.

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 StateProcessExampleEndo or Exo? Solid  LiquidMeltingIce  Water Solid  GasSublimationDry Ice  CO 2 Liquid  SolidFreezingWater  Ice Liquid  GasVaporizationWater  Steam Gas  SolidDepositionSteam  Ice Gas  LiquidCondensationSteam  Water Endo Exo Endo Exo

Two Types of Molar Enthalpy  Molar enthalpy of vaporization: amount of heat energy needed to vaporize one mole of liquid at the liquid’s boiling point.  Molar enthalpy of fusion: amount of heat energy required to melt one mole of solid at the solid’s melting point.  The amount of energy needed is based on the attraction between the molecules. The stronger the attraction, the more energy needed.

Standard 7.c.  Students know energy is released when a material condenses or freezes & is absorbed when a material evaporates or melts.  We will describe the processes that occur to cause a change of state.  We will interpret phase diagrams. Objectives

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 highest temperature and pressure that a substance can exist as a liquid.

Name that state… TemperaturePressureState 70°C2.0 atm 100°C0.5 atm 0°C1.0 atm

Name that state… TemperaturePressureState 70°C2.0 atm 100°C0.5 atm 0°C1.0 atm Liquid Gas Solid

Standard 7.c.  Students know energy is released when a material condenses or freezes & is absorbed when a material evaporates or melts.  We will describe the processes that occur to cause a change of state.  We will interpret phase diagrams. Objectives

Homework  Pg 348 #1-6

Chapter 10.5 Water

Standard 7.c.  Students know energy is released when a material condenses or freezes & is absorbed when a material evaporates or melts.  We will describe the structure of the water molecule and its properties.  We will calculate the amount of energy absorbed or released when water changes state. Objectives

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 ice is kJ/mol  Water boils at 100°C and 1 atm.  Molar enthalpy of vaporization is 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.

Standard 7.c.  Students know energy is released when a material condenses or freezes & is absorbed when a material evaporates or melts.  We will describe the structure of the water molecule and its properties.  We will calculate the amount of energy absorbed or released when water changes state. Objectives

Calculating Amount of Energy  What quantity of energy is released when 804 g of liquid water condenses? Convert from grams to moles Multiply moles by kJ/mol (Vaporization) Moles cancel out, units are kJ Answer = 1820 kJ

Calculating Mass from Energy  What mass of ice is required to release 2000 kJ of energy when melting? Divide kJ by kJ/mol (fusion) kJ cancel out so you have moles. Convert moles to grams. Answer = 5000 g H 2 O

Standard 7.c.  Students know energy is released when a material condenses or freezes & is absorbed when a material evaporates or melts.  We will describe the structure of the water molecule and its properties.  We will calculate the amount of energy absorbed or released when water changes state. Objectives

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