Homework & Formative Assessment Review

Questions??

Check for Understanding Physical Property Chemical Property Blue Color Density Flammability Solubility Reacts with acid to form H2 Supports combustion Volume Melts at 32C Reacts with water to form a gas Baking soda and vinegar form CO2 Diamond scratches wood surface Water boils at 100 C HCl is used to neutralize NaOH by producing water The rock has a shiny, luster appearance

Check for Understanding A physical property is observed with the senses and can be determined without destroying the object. A chemical property indicates how a substance reacts with something else. The original substance is fundamentally changed when observing a chemical property.

Test 1 – 30 minutes Matter Classification of Matter Physical/Chemical Changes-Properties Chemical Reactions COMPLETE INDIVIDUALLY, NO NOTES!! Submit on front table when completed. Review reading Chapter 10 pages 329-351 (342-348) Begin working on Part 4 of Unit Packet!!

Learning Objective(s) I can explain the differences between gases, liquids, and solids using the kinetic molecular theory (KMT) I can analyze phase diagrams and explain phase changes.

States of Matter What happens when a cube of ice is melted?

Nanoscopic Molecules are very close together and densely packed Molecules are closer together but still very separated Molecules are very far apart Shape Will form its own shape and be rigid or fixed Will take the shape of the container Volume Has a constant volume independent of the size of the container Takes the volume of the container Particle motion Local vibration in a fixed position, no long-range motion Random motion throughout the container

Kinetic Molecular Theory These assumptions are true for an ideal gas (hypothetical gas that perfectly fits all assumptions of the kinetic molecular theory) Real gases behave like ideal gases at low pressure and high temperatures.

Kinetic Molecular Theory 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 There are no forces of attraction between gas particles (bounce off) The temperature of a gas depends on the average kinetic energy of the particles of the gas. KE = 1/2mv2 Temperature is a measure of KE

Kinetic Molecular Theory - GASES Expansion No definite shape or volume Fill container and take its shape Fluidity Glide past one another easily Ability to flow and act like liquids (both are “fluids”) Low Density Compressibility Far apart push closer together Volume decreases Diffusion and Effusion Spread out and Mix together Diffusion Spontaneous mixing of particles of two substances caused by random motion Effusion A process by which gas particles pass through a tiny opening Real Gas A gas that does not behave completely according to the assumptions of the kinetic molecular theory High pressure and low temperature

Kinetic Molecular Theory - GASES Describe conditions under which a real gas is not likely to behave ideally. Which of the following gases would you expect to deviate significantly from ideal behavior: Ne, F2, Cl2, CO2, HBr, or NH3? What happens to gas particles when a gas is compressed and cooled?

Kinetic Molecular Theory - Liquids Definite volume and takes shape of its container Particles are in constant motion Closer together in liquids than gases Caused by intermolecular forces Dipole-dipole forces London dispersion forces Hydrogen bonding More ordered than gases Particles not bonded together in fixed positions Move about constantly Fluids Relatively high density Due to close arrangement of particles Relative incompressibility Compress very little because particles are more closely packed together

Kinetic Molecular Theory - Liquids Ability to diffuse Mix with other liquids Slower in liquids than gases High temperature = higher rate of diffusion Surface Tension A force that tends to pull adjacent parts of a liquid’s surface together, thereby decreasing surface area to the smallest possible size. Capillary Action Attraction of the surface of a liquid to the surface of a solid. Evaporation and Boiling Vaporization Liquid or solid changes to a gas Evaporation Particles escape from the surface of a nonboiling liquid and enter a gas state. Formation of Solids Freezing Physical change of a liquid to a solid by removal of energy as heat or solidification

Kinetic Molecular Theory - Liquids Describe a liquid (apply KMT). High Density Diffuse (compare to gases) Evaporate Capillary Action … why does it occur? Difference between vaporization and evaporation, provide an example of both.

Kinetic Molecular Theory - Solids Definite shape and volume Particles are more closely packed than liquid or gas Intermolecular forces are more effective Relatively fixed positions Vibrational movement around fixed points More order Crystalline solids Consist of crystals Crystals are substances in which particles are arranged in an orderly, geometric, repeating patter Amorphous Solids Particles are arranged randomly Glass, plastics Definite Melting Point High Density and Incompressibility Low rate of diffusion

Kinetic Molecular Theory - Solids Describe the solid state. Volume Shape Density Diffusion Amorphous solid vs. crystalline solid?

Water … H2O Diagram of water Hydrogen bonds between water molecules Why does ice float Less dense due to empty space between particles Therefore it only forms on the surface of lakes and insulates the liquid beneath it (prevent total freezing which would kill living things in the lake)

Questions?

Formative Assessment

Average 22/25 (88%) Questions? Next assessment…Tomorrow! Test #1 Analysis Average 22/25 (88%) Questions? Next assessment…Tomorrow!

Phase Change Check-Up List the 6 phase changes. Describe the particle motion between them Use words like: energy, motion, close together, far apart…

Phase Diagrams Identify the following parts of the phase diagram… W P B C W P R

Changes of State Phase: Condensation: Equilibrium: Any part of a system that has uniform composition and properties. See Table 2 page 342 Condensation: The process by which a gas changes to a liquid. Equilibrium: A dynamic condition in which two opposing changes occur at equal rates in a closed system. (i.e. water vapor in bottle)

  Heat Removed The three diagrams above, if viewed from left to right, show the processes of a. melting and then boiling. b. sublimation and then deposition. c. condensation and then freezing. d. a new substance being formed.

Changes of State Diagram of Table 2 pg 342

Phase Diagram A graph of pressure versus temperature that shows the conditions under which the phases of substance exist. The curves represent states of equilibrium between phases. Triple point Indicates the temperature and pressure conditions at which the solid, liquid, and vapor of the substance can coexist at equilibrium. (where all curves meet) Critical point Indicates the critical temperature and critical pressure of a substance. Critical temperature The temperature above which the substance cannot exist in the liquid state. (water 373.99 C) Critical pressure The lowest pressure at which the substance can exist as a liquid at the critical temperature. (water 217.75 atm)

Equilibrium Vapor Pressure of Liquid The pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temperature. Proportional to the concentration of vapor molecules. Volatile liquids Liquids that evaporate readily. Weak forces of attraction between their particles.

Analyzing Phase Diagrams Describe all the changes a sample of solid carbon dioxide would undergo when heated from -85 °C to its critical temperature at a pressure of 1.00 atm. Describe all the changes a sample of solid carbon dioxide would undergo when heated from -85 °C to its critical temperature at a pressure of 73 atm.

Analyzing Phase Diagrams Describe all the changes a sample of carbon dioxide vapor would undergo when cooled from 31.1 °C to -85 °C at a pressure of 8.00 atm.

Analyzing Phase Diagrams At approximately what pressure will carbon dioxide be a vapor at 0 °C ?

Analyzing Phase Diagrams Determine the critical temperature and pressure for carbon dioxide.

Phase Change Check-Up List the 6 phase changes. Describe the particle motion between them Use words like: energy, motion, close together, far apart…

Phase Diagrams Identify the following parts of the phase diagram… W P B C W P R

Exam 2 TOMORROW!!