The Four States of Matter Unit 10: States of Matter Lesson 10.1: States and Their Changes (Review) Solid } Liquid Commonly found on Gas Earth Plasma Based upon particle arrangement Based upon energy of particles Based upon distance between particles Based upon strength of attraction forces between particles SOLIDS Particles of solids are tightly packed, vibrating about a fixed position. Solids have a definite shape and a definite volume. Particle Diagram of a Solid Heat LIQUID Particles of liquids are tightly packed, but are far enough apart to slide over one another. Liquids have an indefinite shape and a definite volume. Heat GAS Particles of gases are very far apart and move freely. Gases have an indefinite shape and an indefinite volume. Heat Particle Diagram of a Gas Particle Diagram of a liquid 1
STATES CHANGES STATE CHANGES Description of State Change Solid to liquid Liquid to solid Solid to Gas Term for State Change Melting or Fusion Freezing or Solidification Sublimation Heat Movement During State Change Heat goes into the solid as it melts Heat leaves the liquid as it freezes. Heat goes into the solid as it sublimates. Description of State Change Liquid to gas Term for State Change Vaporization, which includes boiling and evaporation Gas to liquid Condensation Gas to solid Deposition Heat Movement During State Change Heat goes into the liquid as it vaporizes. Heat leaves the gas as it condenses. Heat leaves the gas as it deposits. But what happens if you raise the temperature to super-high levels between 1000 C and 1,000,000,000 C? Will everything just be a gas? PLASMA A plasma is an ionized gas. A plasma is a very good conductor of electricity and is affected by magnetic fields. Plasmas, like gases have an indefinite shape and an indefinite volume. Plasma is a common state of matter Some places where plasmas are found Hot plasmas 1. Flames SOLID LIQUID GAS PLASMA Tightly packed, in a regular pattern Vibrate, but do not move from place to place Close together with no regular arrangement. Vibrate, move about, and slide past each other Well separated with no regular arrangement. Vibrate and move freely at high speeds Has no definite volume or shape and is composed of electrical charged particles 2
3. Aurora (Northern Lights) 2. Lightning The Sun is an example of a star in its plasma state Cold Plasma A portable plasma flashlight to kill bacteria on the spot [Credit: Xin Pei Lu (Huazhong Uni and IOP Publishing] 3
State Change Diagram (Learn It!) Endothermic Sublimation Melting Vaporization S L G Freezing Condensation Deposition Exothermic Melting = Fusion Freezing = Solidification 19 Equilibrium Any time the rates of opposing processes are equal, those processes are said to be in a state of equilibrium. Phase Equilibrium: Exists at a substances melting point (for solid and liquid phases), and boiling point (for liquid and gas phases). What s in equilibrium at these temps? 20 Kinetic Theory of Matter Kinetic-molecular theory describes the behavior of matter and explains the different properties of solids, liquids, and gases in terms of particles in motion.. Matter is made up of particles which are in continual random motion. Atomic composition affects chemical properties. Atomic composition also affects physical properties. Kinetic Theory of Matter (Cont.) Gases consist of small particles separated by empty space. Gas particles are too far apart to experience significant attractive or repulsive forces. Gas particles are in constant random motion. The Kinetic-Molecular Theory (cont.) Gas particles move in straight paths, changing direction only when colliding with one another or other objects Collisions between gas particles are elastic. An elastic collision is one in which no kinetic energy is lost. The Kinetic energy of a particle depends on mass and velocity (directional speed). Kinetic Energy mass Velocity Temperature is a measure of the average kinetic energy of all the particles in a sample of matter. 4
Explaining the Behavior of Gases Great amounts of space exist between gas particles. Compression reduces the empty spaces between particles. Explaining the Behavior of Gases (cont.) Gases easily flow past each other because there are no significant forces of attraction between the particles. Diffusion the mixing of molecules of two or more substances by "random molecular motion. Effusion: a gas escapes through a tiny hole in its container -Think of a nail in your car tire Graham s Law of Effusion Lighter gas molecules will spread out (effuse) faster than heavier gas molecules. The heavier the gas molecules, The greater the gas density. Diffusion and effusion are explained by Graham s law You will find the densities (and boiling points) for most elements on Reference Table S Thomas Graham (1805 1869) 28 Graham s law of effusion states that the rate of effusion for a gas is inversely proportional to the square root of its molar mass. Graham s law also applies to diffusion Things You Should be Able To Do: 1. A sealed tank has a mixture of ammonia gas (NH 3 ) and carbon dioxide (CO 2 ). A small hole is punctured in the tank and the ammonia gas (NH 3 ) effuses at a rate of 3.6 mol/min. What is the rate of effusion of the carbon dioxide gas? NOT in your Reference Tables! (NEED to MEMORIZE IT!) 30 5
Solution NH 3 molar mass = 17.04 g/mol CO 2 molar mass = 44.01 g/mol X 3. 6mol /min 17.04 mol/g 44.01 mol/g And more Things You Should be Able To Do: 2. A closed container of a mixture of 2.0 moles of each of the gases chlorine, fluorine, neon and helium. The container is opened so the gases can escape. After 10. minutes the container is closed. Arrange the gases remaining in the tank in order of increasing concentration. X = 2.2 mol/min 31 32 Explaining the Behavior of Gases (cont.) Gas particles exert force when they collide with the walls of their container. So. they create pressure Gas Pressure is the force exerted by a gas per unit surface area of an object Depends on: a) force of collisions, and b) number of collisions No particles present? Then there cannot be any collisions, and thus no pressure called a vacuum Explaining the Behavior of Gases (cont.) Atmospheric (Air) pressure results from the collisions of air molecules with objects Decreases as you climb a mountain because.. as elevation increases, fewer particles present, the air layer thins out, the mass of column of air decreases and the number of collisions increases as well. Increases as you go down to Death Valley or the Dead Sea Gas Pressure (Cont.) Barometers are instruments used to measure atmospheric air pressure. Mercury Barometer a straight glass tube filled with mercury (Hg), and closed at one end; placed in a dish of Hg, with the open end below the surface At sea level, the mercury would rise to 760 mm high at 25 o C- called one standard atmosphere (atm) Torricelli invented the barometer. 6
Most modern barometers do not contain mercury - too dangerous These are called aneroid barometers, and contain a sensitive metal diaphragm that responds to the number of collisions of air molecules this is the type in our classroom Standard Pressure 1 standard atmosphere (atm) 101.3 kpa (kilopascals SI Unit) 760 mm Hg (millimeters of mercury) 760 torr 14.7 lbs/in2 13-1 Pressure Either of these: 273 Kelvin (273 K) 0 C And any one of these: 1 atm 101.3 kpa 760 mm Hg 760 torr 14.7 lbs/in 2 (psi) Standard Temperature and Pressure STP Measuring Gas Pressure Manometer: an instrument that uses a column of liquid to measure pressure. The difference in fluid height in a liquid column manometer is proportional to the pressure difference. Open-end Manometer 41 42 7
Measuring Gas Pressure Close-end Manometers Close-end Manometer 44 Pressure conversions 1.000 atm = 101.3 kpa = 760.0 mmhg (or torr) = 14.7 psi Convert 2.35 atm to kpa: 101.3kPa 2.35 atm x = 238 kpa 1 atm Convert 123.4 kpa to atm: 123.4 kpa x 1atm 101.3kPa = 1.218 atm 45 Dalton s Law of Partial Pressures John Dalton (1766 1844) Gases in a mixture exert pressure independently of other gases present. The total pressure exerted by a mixture of gasses is equal to the sum of the pressures exerted by each gas in the mixture. P total = P gasa + P gasb + P gasc +... Also NOT in your Reference Tables (memorize!) 46 If the first three containers are all put into the fourth, we can find the pressure in that container by adding up the pressure in the first 3: 2 atm + 1 atm + 3 atm = 6 atm Partial pressure can be used to calculate the amount of gas produced in a chemical reaction. + + 1 2 3 4 8
A B C D 3/5/2015 Practice Helps Us Learn! 1) What is the total pressure of a mixture of O 2 (g), N 2 (g) and NH 3 (g) if the pressure of the O 2 (g) is 20.0 kpa, N 2 (g) is 60.0 kpa and the NH 3 (g) is 15.0 kpa? 2) A mixture of 1 mole of O 2 and 2 moles of N 2 exerts a pressure of 150. kpa. What is the partial pressure of each gas? 49 50 3) A mixture of 30.0% He and 70.0% Ar exerts a pressure of 150 kpa at 25 o C. What is the partial pressure of each gas? 4) A sample of NH 3 (g) is decomposed into its component elements. If the pressure of the nitrogen gas produced equals 40.0 kpa, what would the pressure of the hydrogen gas be? 51 52 The average of kinetic energy of particles in a substance is measured by its. A. mass B. density C. temperature D. pressure Lesson 13.1-0% 0% 0% 0% Lesson 13.1- One mole of oxygen in a 5.0 liter container has the same partial pressure as one mol of hydrogen in the same container. This is a demonstration of what law? A. law of conservation of mass B. law of definite proportions C. law of conservation of energy D. Dalton s law of partial pressures A B C D 0% 0% 0% 0% 9
The total questions asked by a class of chemistry students equals the sum of the questions asked by each student in the class. John Dalton (1766 1844) Any Questions? 55 10