Agenda 02/14/2011 What is the Kinetic Molecular Theory? OBJECTIVE: Compare and Contrast SOLIDS-LIQUIDS-GASES HWK: CH 13 Vocab and Key Concepts DUE WEDNESDAY

Chapter 13 The States of Matter

Phase Changes Solid Gas Liquid Melting Vaporization Freezing Condensation

Solid Gas Liquid Sublimation Melting Vaporization Freezing Deposition Freezing Condensation

What are the 3 states of matter? Gases -indefinite volume and shape, low density. Liquids- definite volume, indefinite shape, and high density. Solids- definite volume and shape, high density Solids and liquids- have high densities because their molecules are close together.

What is the Kinetic Molecular Theory? Simply Put, the Kinetic Molecular theory says that molecules are in constant random motion. Perfume molecules moving across the room are evidence of this. It describes how molecules behave. It describes gas behavior the best, but can be used for all states of matter.

Gases

What are the 3 assumptions of the KMT? Assumption 1-A Gas is composed of particles usually molecules or atoms Considered to be hard spheres far enough apart that we can ignore their volume. Between the molecules is empty space.

Assumption 2-The particles are in constant random motion. They Move in straight lines until they bounce off each other or the walls. Assumption 3- All collisions are perfectly elastic.

The Average speed of an oxygen molecule is 1656 km/hr at 20ºC The molecules don’t travel very far without hitting each other so they move in random directions.

How does KE relate to Temperature? Temperature is a measure of the Average kinetic energy of the molecules of a substance. The higher temperature the faster molecules will move. At absolute zero (0 K) all molecular motion would stop.

Kinetic Energy and Temperature 13.1 Kinetic Energy and Temperature The red and blue curves show the kinetic energy distributions of a typical collection of molecules at two different temperatures. INTERPRETING GRAPHS a. Inferring Which point on each curve represents the average kinetic energy? b. Analyzing Data Compare the shapes of the curves for cold water and hot water. c. Predicting What would happen to the shape of the curve if the water temperature were even higher? Even lower?

13.1 What is absolute zero? Absolute zero (0 K, or –273.15°C) is the temperature at which the motion of particles theoretically ceases. Particles would have no kinetic energy at absolute zero. Absolute zero has never been produced in the laboratory.

What do we use to measure Gas Pressure? 13.1 What do we use to measure Gas Pressure? A barometer is a device that is used to measure atmospheric pressure. At sea level, air exerts enough pressure to support a 760-mm column of mercury. On top of Mount Everest, at 9000 m, the air exerts only enough pressure to support a 253-mm column of mercury. Calculating What is the decrease in pressure from sea level to the top of Mount Everest?

What are the units of Gas Pressure? 13.1 What are the units of Gas Pressure? The SI unit of pressure is the pascal (Pa). One standard atmosphere (atm) is the pressure required to support 760 mm of mercury in a mercury barometer at 25°C.

Avagadro’s Hypothesis 2 Liters of Helium 2 Liters of Oxygen Has the same number of particles as ..

This is where we get the fact that 22.4 L =1 mole Only at STP 0ºC 1 atm This way we compare gases at the same temperature and pressure.

13.1 Section Quiz. 1. According to the kinetic theory, the particles in a gas are attracted to each other. are in constant random motion. have the same kinetic energy. have a significant volume.

13.1 Section Quiz. 2. The pressure a gas exerts on another object is caused by the physical size of the gas particles. collisions between gas particles and the object. collisions between gas particles. the chemical composition of the gas.

13.1 Section Quiz. 3. The average kinetic energy of the particles in a substance is directly proportional to the Fahrenheit temperature. Kelvin temperature. molar mass of the substance. Celsius temperature.