Chapter 10 The Kinetic-Molecular Theory is based on the idea that particles of matter are always in motion. The constant motion of particles mean they have kinetic energy. Their kinetic energy can be used to explain the different states of matter, (solid, liquid, and gas) and their properties.

ENGAGE - Syringe Activity 1. Pull the plunger of a syringe out as far as it will go without coming out. 2. Put your finger on the end of the syringe (where a needle would go) 3. Push the plunger down. 4. What happens? Draw a picture if needed. 5. Explain why this happens. Use a picture to help explain if needed.

Lemon Initial Model - If I cut open a lemon, draw a model to show what happens that allows you to smell the lemon across the room.

The Kinetic Theory of Gases The Ideal Gas Model explains how ideal gases behave. SIZE: - tiny particles (so small, considered to have no size relative to each other) far away from each other no attraction or repulsion

MOTION: Particles are in constant, rapid, and random motion. When they collide no energy is lost (elastic collisions) When they collide with the walls of a container, they cause pressure.

ENERGY: - Kinetic Energy of gases is determined by: KE = 1/2 mv2 M= mass v= velocity - Temperature is a measure of the average kinetic energy of the gas particles.

Pressure: Measured using: Barometer

Units of Pressure (you will need to be able to convert between these units!) Compared with 1atm Atmospheres (atm) 1.0 atm Kilopascal (kPa) 101.3kPa Millimeters of mercury (mmHg) 760 mmHg torr 760 torr Pounds per square inch (psi) 14.7 psi Inches mercury 29.92 in Hg Pascals (Pa) 101,325 Pa - All of these values are equal to each other

Units of Pressure (you will need to be able to convert between these units!) Example 1: convert 540.0 mmHg to pa

Units of Pressure (you will need to be able to convert between these units!) Example 1: convert 540.0 mmHg to pa 540.0 mmHg x 101,325 pa = 760 mmHg 71994.0  71990 pa

Example 2: convert 50.0 psi to atm Example 3: If a balloon has a pressure of 1,205 torr, how many Kilopascals does this equal?

Example 2: convert 50.0 psi to atm 50.0 psi x 1.0 atm 14.7 psi = 3.40 atm Example 3: If a balloon has a pressure of 1,205 torr, how many Kilopascals does this equal? 1,205 torr x 101.325 Kpa 760 torr = 160.7 Kpa

STP (Standard Temperature and Pressure): Temperature Review: Absolute zero= lowest possible temperature = 0K or -273C STP (Standard Temperature and Pressure): T = 00C or 273K P= 1 atm

Temperature conversions: K = C + 273 C = K - 273 Ex. 1: Convert 400.0 K to Celsius Ex. 2: Convert 60.0 0C to Kelvin

Temperature conversions: K = C + 273 C = K - 273 Ex. 1: Convert 400.0 K to Celsius C = 400 – 273 = 127.0 0C Ex. 2: Convert 60.0 0C to Kelvin K = 60 + 273 = 333 K

Demonstration: diffusion and KMT What do you predict what will happen to a drop of food colouring that is added to each graduated cylinder- one HOT one COLD? 2. What is happening in each graduated cylinder at the macroscopic (visual) level? 3. What is happening in each graduated cylinder at the particle level? MODEL THIS! 4. What do you think the graduated cylinders will look like by the end of class? Explain why this happens.

Molecular Effusion and Diffusion Gas particles are always moving Their speed depends on the mass of particles On average lighter gases move FASTER than heavier gases (have same average kinetic energy so they need higher velocity to make up for less mass)

Graham’s Law of Effusion Effusion is the escape of a gas through a tiny hole (a balloon will deflate over time due to effusion).

Diffusion The spread of gas through space. After watching the video on Bromine answer the following questions: Why does the gas diffuse? Why does it take more time than you would expect?

Diffusion The spread of gas through space. After watching the video on Bromine answer the following questions: Why does the gas diffuse? - random motion of the molecules Why does it take more time than you would expect? - they are moving very fast, but collide with the air molecules

Which will effuse faster: CH4 or Xe ? Explain why a a gas will diffuse faster in hot air than cold air?