Behavior of Gases. Airbags fill with N 2 gas in an accident. Gas is generated by the decomposition of sodium azide Gas molecules save your life! 2 NaN.

Slides:



Advertisements
Similar presentations
I. Physical Properties 9 (A) describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described.
Advertisements

Kinetic Molecular Theory. What if… b Left a basketball outside in the cold… would the ball appear to be inflated or deflated? b Which picture box do you.
Physical Properties Gases. Kinetic Molecular Theory b Particles in an ideal gas… have no volume have elastic collisions are in constant, random, straight-line.
Chapter 10 Gases No…not that kind of gas. Kinetic Molecular Theory of Gases Kinetic Molecular Theory of Gases – Based on the assumption that gas molecules.
Chapter Pressure Macro-Scale Pressure is the amount of force exerted over a given area  Familiar unit is “pounds per square inch” or psi (tire.
I. Physical Properties Ch 12.1 & 13 Gases. Kinetic Molecular Theory 1. Particles of matter are ALWAYS in motion 2. Volume of individual particles is 
Lesson 1: The Nature of Gases UNIT 9 – GAS LAWS Chapter 13 and 14.
Think About This… Gas Atmosphere This is a U-Tube Manometer. The red stuff is a liquid that moves based on the pressures on each end of the tube. Based.
Gas Laws Gas Laws highly compressible. occupy the full volume of their containers. exert a uniform pressure on all inner surfaces of a container diffuse.
Gases and Gas Laws Chemistry– Unit 11: Chapter 14
I. Physical Properties Ch Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. have elastic collisions. are in constant,
C. Johannesson I. Physical Properties (p ) Ch. 10 & 11 - Gases.
CH 11 – Physical Characteristics of Gases: Objectives Describe how the kinetic-molecular theory of matter explains ideal gases Differentiate between ideal.
2 CHAPTER 12 GASES The Gas Laws u Describe HOW gases behave. u Can be predicted by the theory. u Amount of change can be calculated with mathematical.
GASES. Importance of Gases Airbags fill with N 2 gas in an accident. Airbags fill with N 2 gas in an accident. Gas is generated by the decomposition of.
Honors Chem Ch. 10 Physical Characteristics of Gases 10.1 Kinetic Molecular Theory Pressure The Gas Laws Boyle, Charles, Gay-Lussac, combined,
Gases. Particles in an ideal gas… have no volume. have elastic collisions. are in constant, random, straight-line motion. don’t attract or repel each.
Properties and Measuring Variables Gases Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. have elastic collisions. are.
I. Physical Properties (p ) Ch. 10 & 11 - Gases.
Ch. 10 Gases. Characteristics of Gases b Gases expand to fill any container. random motion, no attraction b Gases are fluids (like liquids). no attraction.
A theory concerning the thermodynamic behavior of matter, especially the relationships among pressure, volume, and temperature in gases. Kinetic Molecular.
I. Physical Properties Ch Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. have elastic collisions. are in constant,
I. Physical Properties Ch Gases. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. have elastic collisions. are in constant,
II. Gas Laws Topic 10 Gases. A. Boyle’s Law P V PV = k.
? Gases Chapter 4. ? Kinetic Molecular Theory Particles in an Ideal Gases…  have no volume.  have elastic collisions.  are in constant, random, straight-line.
Physical Properties Gases. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. The particles in a gas are very far apart. have elastic.
I. Physical Properties Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. have elastic collisions. are in constant, random,
BEHAVIOR OF GASES Chapter THREE STATES OF MATTER 2.
I. Physical Properties. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. have elastic collisions. are in constant, random, straight-
I. Physical Properties Gases. A. Kinetic Molecular Theory b kinetic-molecular theory: (def) theory of the energy of particles and the forces that.
Physical Properties Ch. 10 & 11 - Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. have elastic collisions. are in constant,
Ch. 10 Gases. Characteristics of Gases b Gases expand to fill any container. random motion, no attraction b Gases are fluids (like liquids). no attraction.
I. Physical Properties Gases Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no (very small) volume. have elastic collisions. are.
Gases Gas Animations. Kinetic Molecular Theory Particles in an ideal gas… –have no volume. –have elastic collisions. –are in constant, random, straight-line.
I. Physical Properties Ch Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. have elastic collisions. are in constant,
Physical Properties Gases. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. have elastic collisions. are in constant, random, straight-
GASES. Importance of Gases Airbags fill with N 2 gas in an accident. Airbags fill with N 2 gas in an accident. Gas is generated by the decomposition of.
I. Physical Properties Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume. The particles in a gas are very far apart. have.
The Property of Gases – Kinetic Molecular Theory explains why gases behave as they do
Dalton’s Law of Partial Pressures P total =P 1 +P 2 +…. Total pressure of a mixture of gases in a container is the sum of the individual pressures (partial.
The Gas Laws 1. A gas is composed of particles molecules or atoms – hard spheres far enough apart- ignore volume Empty space The Kinetic Theory of Gases.
I. Physical Properties I. Gases I. Gases. Nature of Gases b Gases have mass. b They can be compressed. b They completely fill their containers. b Representative.
I. Physical Properties Ch Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have mass but no definite volume. have elastic collisions.
BellringerBellringer b An average human heart beats 60 times per minute. If the average person lives to the age of 75, how many times does the average.
AN INTRODUCTION To Gases What is a GAS? Solid Liquid Gas.
Gases I. Physical Properties.
Behavior of Gases.
Gases.
I. Physical Properties (p )
Ch.12- Gases I. Physical Properties.
I. Physical Properties (p )
I. Physical Properties (p )
Gases I. Physical Properties.
Gases.
Gas laws.
Gases Physical Properties.
Unit 8: Gases and States of Matter
Gases I. Physical Properties.
I. Physical Properties (p. 303 – 312 in school)
Gases I. Physical Properties 9 (A) describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as.
Ch Gases I. Physical Properties.
The Gas Laws Boyle’s Law Charles’ Law Gay-Lussac’s Law Avogadro’s Law.
Properties and Measuring Variables
Ch Gases I. Physical Properties.
Ch Gases I. Physical Properties.
Gases Physical Properties.
The Kinetic-Molecular Theory of Gases
Chapter 7-1, 7-2.
Gases and Laws – Unit 2 Version
Presentation transcript:

Behavior of Gases

Airbags fill with N 2 gas in an accident. Gas is generated by the decomposition of sodium azide Gas molecules save your life! 2 NaN 3 ---> 2 Na + 3 N 2 Example of Importance of Gases

Kinetic Molecular Theory (KMT) Particles in an ideal gas… Particles in an ideal gas… have no volume. have no volume. have elastic collisions. have elastic collisions. are in constant, random, straight-line motion. are in constant, random, straight-line motion. don’t attract or repel each other. don’t attract or repel each other. have an avg. KE directly related to Kelvin temperature. have an avg. KE directly related to Kelvin temperature.

Real Gases Particles in a REAL gas… Particles in a REAL gas… have their own volume have their own volume attract each other attract each other Gas behavior is most ideal… Gas behavior is most ideal… at low pressures at low pressures at high temperatures at high temperatures when very small in size when very small in size when nonpolar when nonpolarPLIGHT

Characteristics of Gases Gases expand to fill any container uniformly. Gases expand to fill any container uniformly. Are in random motion, have no attraction Are in random motion, have no attraction Gases have very low densities. Gases have very low densities. Particles have no volume = lots of empty space Particles have no volume = lots of empty space

Characteristics of Gases There is a lot of “free” space in a gas. There is a lot of “free” space in a gas. Gases can be compressed. Gases can be compressed. no volume = lots of empty space no volume = lots of empty space

Gases undergo diffusion & effusion. Gases undergo diffusion & effusion. Are always in random motion Are always in random motion Smaller and lighter gas particles do this faster Smaller and lighter gas particles do this faster

Gas Pressure Which shoes create the most pressure?

What Causes Pressure? What Causes Pressure? oleculartheory/Pressure.html oleculartheory/Pressure.html oleculartheory/Pressure.html oleculartheory/Pressure.html

Factors Affecting Gas Pressure Number of Moles (Amount of gas) Number of Moles (Amount of gas) As # of particles increase, the number of collisions with the container wall increases. As # of particles increase, the number of collisions with the container wall increases. Volume Volume Smaller the volume, the greater the pressure exerted on the container. Smaller the volume, the greater the pressure exerted on the container. Temperature Temperature As temp. increases, KE increases, this increases frequency of collisions making pressure increase. As temp. increases, KE increases, this increases frequency of collisions making pressure increase.

Measuring Gas Pressure Barometer Barometer measures atmospheric pressure measures atmospheric pressure (developed by Torricelli in 1643) (developed by Torricelli in 1643) Mercury Barometer Aneroid Barometer

Standard Pressure (Sea Level) Standard Pressure (Sea Level) kPa (kilopascal) 1 atm 760 mm Hg (also called torr) You may be asked to convert between units of pressure!

Hg rises in tube until force of Hg (down) balances the force of atmosphere (pushing up). (Just like a straw in soft drink) Column height measures pressure of atmosphere 1 standard atmosphere (atm) = 760 mm Hg (or torr)

Measuring Gas Pressure Manometer Manometer measures contained gas pressure measures contained gas pressure U-tube Manometer

Working with Formulas The Gas Laws

Temperature ºC K K = ºC Always use absolute temperature (Kelvin) when working with gases. Always use absolute temperature (Kelvin) when working with gases.

Gas properties can be modeled using math. Model depends on: V = volume of the gas (L) V = volume of the gas (L) T = temperature (K) T = temperature (K) ALL temperatures MUST be in Kelvin!!! ALL temperatures MUST be in Kelvin!!! n = amount (moles) n = amount (moles) P = pressure (atmospheres or kPa) P = pressure (atmospheres or kPa)

Standard Temperature & Pressure 0°C 1 atm 273 K kPa 760 mmHg -OR- STP

Boyle’s Law The pressure and volume of a gas are inversely related The pressure and volume of a gas are inversely related at constant mass & temp at constant mass & temp P V PV = k Robert Boyle ( ). Son of Earl of Cork, Ireland.

Boyle’s Law Since P x V is always a constant: P 1 x V 1 = P 2 x V 2

Pressure and Volume Relationship son.edu/vce/kineticm oleculartheory/PV.htm l

If Mass and Temp are Constant

Boyle’s Law Balloon in a Vacuum

V T Charles’ Law The volume and absolute temperature (K) of a gas are directly related The volume and absolute temperature (K) of a gas are directly related at constant mass & pressure at constant mass & pressure Jacques Charles ( ). Isolated boron and studied gases. Balloonist.

Charles’ Law Since V/T is always a constant: V 1 = V 2 T 1 T 2

If Mass and Pressure are Constant

Charles’ Law hfiles/gaslaw/charles_law.html Pour Liquid Nitrogen on Balloon!!

P T Gay-Lussac’s Law The pressure and absolute temperature (K) of a gas are directly related The pressure and absolute temperature (K) of a gas are directly related at constant mass & volume at constant mass & volume

Gay – Lussac’s Law Since P/T is always a constant: P 1 = P 2 T 1 T 2

Pressure and Temperature Relationship Pressure and Temperature Relationship /PT.html /PT.html /PT.html /PT.html

Review of 3 Gas Laws Summary of Changing Variables Summary of Changing Variables sentialchemistry/flash/gasesv6.swf sentialchemistry/flash/gasesv6.swf

P1V1T1P1V1T1 = P2V2T2P2V2T2 P 1 V 1 T 2 = P 2 V 2 T 1 The good news is that you don’t have to remember all three gas laws! We can combine them into a single equation. If you should only need one of the other gas laws, you can cover up the item that is constant and you will get that gas law! Combined Gas Law (on Ref Table)

Example Set up Data Table P 1 = atm V 1 =.180 L T 1 = 302 K P 2 = 3.20 atm V 2 =.090 L T 2 = ?? A sample of helium gas has a volume of L, a pressure of atm and a temperature of 29°C. What is the new temperature (°C) of the gas at a volume of.090 L and a pressure of 3.20 atm?

GIVEN: V 1 = 473 ml T 1 = 36°C = 309K V 2 = ? T 2 = 94°C = 367K WORK: P 1 V 1 T 2 = P 2 V 2 T 1 Gas Law Problems A gas occupies 473 ml at 36°C. Find its volume at 94°C. A gas occupies 473 ml at 36°C. Find its volume at 94°C. CHARLES’ LAW TT VV (473 ml )(367 K)=V 2 (309 K) V 2 = 562 ml

GIVEN: V 1 = 100. mL P 1 = 150. kPa V 2 = ? P 2 = 200. kPa WORK: P 1 V 1 T 2 = P 2 V 2 T 1 Gas Law Problems A gas occupies 100. mL at 150. kPa. Find its volume at 200. kPa. A gas occupies 100. mL at 150. kPa. Find its volume at 200. kPa. BOYLE’S LAW PP VV (150.kPa)(100.mL)=(200.kPa)V 2 V 2 = 75.0 mL

GIVEN: V 1 = 7.84 ml P 1 = 71.8 kPa T 1 = 25°C = 298 K V2 = ?V2 = ? P 2 = kPa T 2 = 273 K WORK: P 1 V 1 T 2 = P 2 V 2 T 1 (71.8 kPa)(7.84 ml)(273 K) =( kPa) V 2 (298 K) V 2 = 5.09 ml Gas Law Problems A gas occupies 7.84 ml at 71.8 kPa & 25°C. Find its volume at STP. A gas occupies 7.84 ml at 71.8 kPa & 25°C. Find its volume at STP. P  T  VV COMBINED GAS LAW

GIVEN: P 1 = 765 torr T 1 = 23°C = 296K P 2 = 560. torr T 2 = ? WORK: P 1 V 1 T 2 = P 2 V 2 T 1 Gas Law Problems A gas’ pressure is 765 torr at 23°C. At what temperature will the pressure be 560. torr? A gas’ pressure is 765 torr at 23°C. At what temperature will the pressure be 560. torr? GAY-LUSSAC’S LAW PP TT (765 torr)T 2 = (560. torr)(309K) T 2 = 226 K = -47°C

Dalton’s Law of Partial Pressures P total =P 1 +P 2 +…. P total =P 1 +P 2 +…. Total pressure of a mixture of gases in a container is the sum of the individual pressures (partial pressures) of each gas, as if each took up the total space alone. Total pressure of a mixture of gases in a container is the sum of the individual pressures (partial pressures) of each gas, as if each took up the total space alone. This is often useful when gases are collected “over water” This is often useful when gases are collected “over water”

Dalton’s Law of Partial Pressures The total pressure of a mixture of gases equals the sum of the partial pressures of the individual gases. The total pressure of a mixture of gases equals the sum of the partial pressures of the individual gases. P total = P 1 + P P atm = P H2 + P H2O

GIVEN: P H2 = ? P total = 94.4 kPa P H2O = 2.72 kPa WORK: P total = P H2 + P H2O 94.4 kPa = P H kPa P H2 = 91.7 kPa Dalton’s Law Hydrogen gas is collected over water at 22.5°C. Find the pressure of the dry gas if the atmospheric pressure is 94.4 kPa. Hydrogen gas is collected over water at 22.5°C. Find the pressure of the dry gas if the atmospheric pressure is 94.4 kPa. Look up water-vapor pressure on for 22.5°C. Sig Figs: Round to least number of decimal places. The total pressure in the collection bottle is equal to atmospheric pressure and is a mixture of H 2 and water vapor.

GIVEN: P gas = ? P total = torr P H2O = 42.2 torr WORK: P total = P gas + P H2O torr = P H torr P gas = torr A gas is collected over water at a temp of 35.0°C when the barometric pressure is torr. What is the partial pressure of the dry gas? A gas is collected over water at a temp of 35.0°C when the barometric pressure is torr. What is the partial pressure of the dry gas? DALTON’S LAW Look up water-vapor pressure for 35.0°C. Sig Figs: Round to least number of decimal places. Dalton’s Law The total pressure in the collection bottle is equal to barometric pressure and is a mixture of the “gas” and water vapor.

Graham’s Law Diffusion Diffusion Spreading of gas molecules throughout a container until evenly distributed. Spreading of gas molecules throughout a container until evenly distributed. Effusion Effusion Passing of gas molecules through a tiny opening in a container Passing of gas molecules through a tiny opening in a container

Graham’s Law Speed of diffusion/effusion Speed of diffusion/effusion Kinetic energy is determined by the temperature of the gas. Kinetic energy is determined by the temperature of the gas. At the same temp & KE, heavier molecules move more slowly. At the same temp & KE, heavier molecules move more slowly.

V n Avogadro’s Principle Equal volumes of gases contain equal numbers of moles at constant temp & pressure true for any gas Equal volumes of gases at the same T and P have the same number of molecules.