1. Chapter 10 States of Matter

2. 10.1 Kinetic Molecular Theory (KMT) “Particles of Matter are always in motion” States of Matter We will discuss the KMT in terms of : 1. Gases 2. Liquids 3. Solids

3. KMT - Gases O Ideal gas- follows all of the tenets of the KMT. O 1. Gases consist of large numbers of atoms/molecules that are in continuous, random motion. O 2. The combined volume of all the atoms/molecules of the gas is negligible relative to the total volume in which the gas is contained.

4. Gases Cont. O 3. Attractive and repulsive forces between gas particles is negligible. O 4. Energy can be transferred between particles during collisions, but the average kinetic energy of the particles does not change with time (assuming temperature is constant) = collisions are elastic O 5. The average kinetic energy of the particles is proportional to the absolute temperature. O K.E. = ½ mv 2

5. Properties of Gases O Expansion-gases occupy the volume of the container they are enclosed in. O Fluidity- gas particles move like liquids because there are no attractive or repulsive forces among them O Density- gases have low densities because of the large amounts of space between the particles.

6. Properties of Gases Cont. O Compressibility- Gases can be easily condensed with an increase in pressure due to the large space between the particles. O Diffusion- the random mixing of particles due to their constant motion. O Effusion- gas particles pass through a tiny opening. O Rate is directly proportional to the velocities of the particles. (Smaller particles move faster and vice-versa)

7. Real Gases O Those that do not conform to the 5 parts of the KMT. O When gases are held at high pressure and low temperatures they deviate from their expected behavior. O Noble gases conform the most to the KMT and act like ideal gases. O The more polar the gas molecule the more it deviates from the KMT and acts like a real gas.

8. 10.2 Liquids O Have a definite volume and take the shape of its container O Particles are closer together so their attractive forces are stronger than in gases (think strength of intermolecular forces) O Fluid – the ability to flow and occupy the shape of its container.

9. Liquids Cont. O Density – fairly high considering the closer arrangement of the particles O Incompressibility- because of the close proximity to one another, the particles in a liquid can’t be pushed much closer together. O Diffusion- liquids move easily among other liquids. Attractive forces and temperature of the particles lends to a slower diffusion rate of the liquid particles.

10. Liquids Cont. O Surface Tension- a force that attracts adjacent particles on a liquids’ surface together enough to decrease the surface area. O The higher the intermolecular forces the higher the surface tension. O Water has a fairly high surface tension.

11. Liquids Cont. O Capillary Action – the attraction of the surface of a liquid to the surface of a solid. O Meniscus O Chromatography O Phloem tubes in plants

12. Liquids Cont. O Vaporization – liquid changing to a gas O Evaporation – vaporization at the surface of a liquid O Individual particles gain enough kinetic energy to break the I.F. and escape as a gas. O Freezing – liquid changing to a solid O Due to the increased intermolecular attractions among the particles

13. 10.3 Solids O Highly ordered arrangement with minimal movement among the particles O I.F. exert stronger forces due to this proximity O Types: O Crystalline- geometric, repeating pattern of particles O Amorphous- random arrangement of particles O Glass, obsidian O “without shape”

14. Solids Cont. O Melting- changing a solid to a liquid by applying heat energy O Overcome I.F. and break apart from the crystalline structure O Supercooled liquids (amorphous solids) – retain some liquid properties due to their lack of a uniform, organized pattern O High Density O Low diffusion rate

15. Solids Cont. O Types of Crystals (p. 340) O 1. Ionic - NaCl O 2. Covalent Network – SiO 2 O 3. Metallic - Cu O 4. Covalent Molecular – NH 3

16. Changes of State O Phase – when a substance has uniform composition and properties O Melting, freezing, vaporization, condensation, sublimation, deposition O Equilibrium – when two phases occur at the same rate. E.g., melting freezing

17. Changes of State Cont. O Equilibrium Vapor Pressure – the pressure exerted by a vapor in equilibrium with its liquid at a given temp. O Proportional to the concentration of molecules in the vapor phase. O Increases with an increase in temperature O Volatile liquids (those that evaporate easily) have higher V.P. because they tend to have weaker I.F. between the molecules. O Vapor Pressure Animation Vapor Pressure Animation

18. Changes of State Cont. O Boiling – change of a liquid to vapor at the surface and within the liquid. O Boiling point – when the V.P. equals the atmospheric pressure. O Normal B.P. of water = 100 o C, (normal atmospheric pressure of 1 atm, 760 torr, 101.3 kPa) O B.P. Animation B.P. Animation

19. Vapor Pressures of Various Substances

20. Identity of Substances O A – Diethyl ether O B – Benzene O C - water

21. Phase Diagrams O Phase Diagram Explanation Phase Diagram Explanation

22. Phase Diagram for Water