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Unformatted text preview: Reading: The Mathematical Reading: Relationships in Data Relationships
Read and Take Notes Key Points: Can you describe each relationship in one sentence? one What does the graph look like for each relationship? each What is the generic equation for each relationship? relationship? 1 Gases (or Gasses) vs Vapor Gases vs
Gas: A substance that is normally in the substance gaseous state at STP. gaseous
T = O0 C P = 1 atm atm Vapor: A substance that can become a gas, substance but is a solid or liquid at STP. but Kinetic Molecular Theory
Describes the behavior of the particles Describes (atoms or molecules) that make up a gas. gas. Postulates of the theory: Gases consist of extremely small particles, each of which has mass. particles, The distances separating these particles is very large. particles 2 Kinetic Molecular Theory
Postulates of the theory: The volume of the gas particles themselves is assumed to be zero. themselves Volume of a gas = volume of the Volume container container Gas particles are in constant rapid and random motion. and Gases diffuse 100% Kinetic Molecular Theory
Postulates of the theory: Collisions of gas particles with each other or the walls of their container are perfectly elastic AND even. even. No energy is lost in No these collisions. these Exert an even Exert pressure on the wall of their container of 3 Kinetic Molecular Theory
Postulates of the theory: The average kinetic energy of a gas particle depends only on the temperature the gas is at. temperature Gas particles exert no force on one another. another. Attractive forces between gas Attractive particles is so weak that they are assumed to be zero. assumed 4 Variables of a Gas
1. Amount of Gas (n) Expressed in term of moles of gas (n). (n). 2. Volume (V) A gas will uniformly fill any container it is placed in. container Volume of the gas = volume of the container it is placed in. container Volume (V) = usually expressed in liters 4 4 Variables of a Gas
3. Temperature (T) Reported in Kelvin (K) Reported (K) = (0C) + 273 (K) 4 Variables of a Gas
4. Pressure (P) The force exerted on the containers walls when gas molecules or particles collide with the wall. with Usually expressed in atm. in Atmospheric Atmospheric Pressure Pressure Force of the Earth’s air Earth air pushing down 5 Pressure
Measured using a Measured barometer. barometer. Pressure Conversions: 1 atmosphere (atm) = 101,325 pascals (Pa) 101,325 pascals 1 atm = 760 mm Hg = 760 torr atm 760 torr 2 1 atm = 14.7 lb/in atm 1 bar = 100,000 Pa = 0.9869 atm bar atm 1000 Pa = 1 kilopascal (kPa) Sir Robert Boyle (1627 – 1691) Sir
Investigated the Investigated relationship between the pressure and the volume of a gas. volume Used a barometer Used Held temperature and the number of moles constant. constant. 6 Boyle’s Law Demonstration
Graph pressure (yaxis) vs volume (xaxis) axis) vs For each data set, calculate pressure x For volume volume Boyle’s Law Demonstration
Questions: Based on your graph, what type of Based relationship do pressure and volume demonstrate? demonstrate? Based on your calculations, what is the Based relationship between pressure and volume? relationship Write an equation that demonstrate the Write relationship between pressure and volume. relationship volume Why do temperature and the number of Why moles of gas have to be held constant for this equation to be true? this 7 Boyle’s Law
The pressure and the volume of a sample of The gas at constant temperature are inversely proportional to each other. proportional Pressure x Volume = constant P1 x V 1 = P2 x V 2 Constants: •Quantity of gas •Temperature of gas Variables: •Pressure of gas •Volume of gas Boyle’s Law: Why?
As volume decreases, pressure As increases. Why? increases. •As the volume decreases, the number of As collisions between molecules and the wall of their container increases. of As volume increases, pressure As decreases. Why? decreases. •As the volume increases, the number of As collisions between molecules and the wall of their container decreases. wall 8 PhET Demo Boyle’s Law Sample Problem
I have added 15 L of air to a balloon at have sea level (1.0 atm). If I take the balloon atm). with me to Denver, where the air pressure is 0.85 atm, what will the new atm what volume of the balloon be? volume Constants: n and T P1 V1 = P2 V2 (1.0 atm)(15 L) = (0.85 atm)(x) x = 18 L 9 Closing Thoughts
Air Hogs Split Shot Air Rocket Rocket Based on your new Based found knowledge of gasses, explain how it works! works! HW
Complete the Boyle’s Law WS 10 ...
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 Spring '10
 ANDERSON
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