Please get out a clean page #122 Set up your Cornell Notes: Topic: Kinetic Molecular Theory of Gases Obj: #9 – describe the postulates of the KMT ESQ: How can we formulate the postulates of the KMT based on our prior knowledge of gas behavior?

Set up a small chart that looks like this… (maybe use 5-6 lines) K – KNOWW – WANT TO KNOW L - LEARNED List 3 specific things that you KNOW or WANT TO KNOW about gases or gas behavior. Try to be unique!

Kinetic Molecular Theory and Gas Laws You have about 15 minutes to read the passage and take Cornell notes over the content. Make sure to “chunk” notes to leave room for comments, questions or additions.

Kinetic-Molecular Theory – explains how particles in matter behave 1. All matter is composed of small particles that are far apart. Gas is mostly empty space. 2. Particles are in constant, random motion. 3. Particles collide with each other and walls of their containers: collisions create pressure 4. Collisions are elastic = no KE lost 5. No attractive/repulsive forces between particles. Molecules move in straight lines.

PHASESOLIDLIQUIDGAS Kinetic EnergyLowMediumHigh ShapeRigidFluidFluid – fills container; diffusion ForcesStrongMediumWeak VolumeDefinite Indefinite CompressibilityIncompressible COMPRESSIBLE! “squish!” DensityHigh (particles close together) MediumLow (spread out)

Get out another clean sheet of paper… #123 TOPIC: Factors affecting gases OBJ: Understand the principles that influence gas behavior. ESQ: How do I interpret the conditions that affect gas behavior?

EXIT QUESTIONS: 1) Each of these flasks contains the same number of molecules. Which container has the highest pressure? Explain your answer.

EXIT QUESTIONS: 2)Which of the following changes to a system will NOT result in an increase in pressure? Explain why you chose your answer. a)Increasing the volume of container b)adding more gas molecules c)Decreasing the volume of the container d)Raising the temperature

Factors affecting gases 1.Volume – amount of space an object occupies Measured in milliliters (mL) or Liters (L) 1000 mL = 1 L We already have heard that 1 mol = 22.4 STP The more moles we have the bigger the balloon will need to be !

Example 1 How many moles of nitrogen gas are in 89.6 L at STP? 89.6 L N 2 1 mol N L N 2 = 4 mol N 2

Example 2: What volume does 76 grams of fluorine (F 2 ) occupy at STP (normal conditions)? 76 g F 2 38 g F 2 1 mole F L F 2 = 44.8 L F 2

2. Temperature  Average kinetic energy of particles (how fast they go)  Measured in Kelvin  K = o C Ex: Convert 17 o C to Kelvin: 17 o C = 290 K

3. Pressure Force exerted by a gas per unit area on a surface. Example: Pounds/in 2 or psi Results from the simultaneous collisions of billions of gas particles with the walls of the vessel containing the gas. Standard pressure: 760 mm Hg = 1 atmosphere = kPa = in. Hg = 14.7 psi = 760 torr

Measuring Atmospheric Pressure Measured with a barometer. A barometer uses a column of mercury that rises to an average height of 760 mmHg at sea level. 1 atmosphere (1 atm)

Standard Temperature and Pressure (STP) The conditions of standard temperature and pressure are = 1.0 atm pressure and = 273 K (or 0  1 mole of gas = 22.4 L of gas

The atmospheric pressure in Denver, CO is atm on average. Express this pressure in mm Hg.

Example 2 Convert a pressure of 175 kPa to atmospheres.

Weekend Weather HW City & Time Recorded? Temperature °C Temperature K Pressure (inches Hg) Pressure 1.Fort Worth, TX mm Hg? 2. torr? 3. kPa? 4. Mm Hg? 5. kPa?