CHEMISTRY 2013-2014 THE BEHAVIOR OF GASES. VARIABLES THAT DESCRIBE A GAS Compressibility: a measure of how much the volume of matter decreases under pressure.

Slides:



Advertisements
Similar presentations
Gas Laws.
Advertisements

Gases doing all of these things!
Gases Laws Notes. Pressure Pressure- force per unit area caused by particles hitting the walls of a container Barometer- Measures atmospheric pressure.
Warm Up 4/9 Write the formula of magnesium chloride.
Chapter 10 PHYSICAL CHARACTERISTICS OF GASES
Gas Laws.
Drill 4/16/2015 What do you think is the oldest form of human flight? How does it work?
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.
Gas Law and Gas Behavior
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.
The Gas Laws.
Chapter 13: Gases. What Are Gases? Gases have mass Gases have mass.
GAS LAWS Add a picture or 2..
Chapter 14 – Gases Kinetic Molecular Theory (KMT) Defn – describes the behavior of gases in terms of particle motion Defn – describes the behavior of.
Gases Notes A. Physical Properties: 1.Gases have mass. The density is much smaller than solids or liquids, but they have mass. (A full balloon weighs.
CH 11 – Physical Characteristics of Gases: Objectives Describe how the kinetic-molecular theory of matter explains ideal gases Differentiate between ideal.
Gases
Now, a little more about Gases!. Boyle’s Law The volume of a gas is inversely related to the pressure at a constant temperature. P 1 V 1 = P 2 V 2.
Gases. States of Matter Solid: Definite Shape Definite Volume Incompressible Liquid: Indefinite Shape Definite Volume Not Easily Compressed Gas: Indefinite.
Gases.
What affects the behavior of a gas? u The number of particles present u Volume (the size of the container) u Temperature 2.
We NEED Air to Breathe!!! Gases form homogeneous mixtures with each other regardless of the identities or relative proportions of the component gases Air.
Gases Chapter 13.
Chapter Six Gas Laws –Properties of Gases –Gas Pressure –Empirical Gas Laws Boyle’s, Charles’ and Gay-Lussac’s –Combined Gas Law –Avogadro’s Law –Dalton’s.
GASES.
11.1 The volume occupied by a gas is mostly empty space.
GAS LAWS Chapter 10.
Gas!!! It’s Everywhere!!!!.
Chapter 13: Gases. What Are Gases? Gases have mass Gases have mass Much less compared to liquids and solids Much less compared to liquids and solids.
Gas Laws and Gas Stoichiometry. Kinetic –Molecular Theory Particles of matter (solid, liquid, or gas) are always in motion. This motion has consequences.
Gases.  State the kinetic-molecular theory of matter, and describe how it explains certain properties of matter.  List the five assumptions of the kinetic-
TEKS 9A: Describe and calculate the relations between volume, pressure, number of moles, and temperature for an ideal gas as described by Boyle’s law,
Gases Chapter 13. Kinetic-Molecular Theory of Matter Model for gases Explains why gases behave the way that they do Based on the idea that particles of.
Gases Dr. Chin Chu River Dell Regional High School
Chapter 6 Gases. Kinetic Molecular Theory of Gases Small particles moving continually and randomly with rapid velocities in straight lines Attractive.
Gases Ch.10 and 11. Kinetic-Molecular Theory 1.Gases consist of very small particles that are far apart Most particles are molecules Volume of particles.
Gases. Elements that exist as gases at 25 0 C and 1 atmosphere.
The Gas Laws A Tutorial on the Behavior of Gases..
Chapters 10 and 11: Gases Chemistry Mrs. Herrmann.
Review of Gases. The nature of gases… Gases all have common physical properties: 1)Mass 2)Easily compressible 3)Take the shape of their container 4)Can.
CHEMISTRY THE BEHAVIOR OF GASES. VARIABLES THAT DESCRIBE A GAS Compressibility: a measure of how much the volume of matter decreases under pressure.
Chapter 11: Gases. Section 1: Gases and Pressure.
Note: You must memorize STP and the gas laws!!. The Kinetic Molecular Theory states that gas particles are ____________ and are separated from one another.
The Gas Laws u The gas laws describe HOW gases behave. u They can be predicted by theory. u The amount of change can be calculated with mathematical.
KINETIC MOLECULAR THEORY Physical Properties of Gases: Gases have mass Gases are easily compressed Gases completely fill their containers (expandability)
SI unit of pressure- pascal (Pa) Standard atmospheric pressure = 101
Gas Laws. 1. Kinetic Molecular Theory Ideal Gases :  Gas particles do not attract or repel each other.  Gas particles are much smaller than the distances.
Gases. Kinetic Theory of Gases Explains Gas behavior: 4 parts: 1) Gas particles do not attract or repel each other (no I.M. forces).
Chapter 11: Gases. Section 1: Gases and Pressure.
Pages Chp 11 Gas Laws. Boyle’s Law P V PV = k.
Characteristics of Gases The Kinetic-Molecular Theory of Matter Pressure The Gas Laws.
 5.1 Substances that exist s gases  5.2 Pressure of the gas  5.3 The gas laws  5.4 Ideal gas equation  5.5 Gas stoichiometry  5.6 Dalton’s Law of.
II. The Gas Laws (p ) Ch. 10 & 11 - Gases.
Gases HW: read CH 13.
Behavior of Gases. Gases exert Pressure Due to collisions of particles Barometer Review units Compression of gas absorbs E.
BEHAVIOR OF GASES Gases have weight Gases take up space Gases exert pressure Gases fill their containers Gases are mostly empty space (the molecules in.
THE GAS LAWS AVOGADRO’S, BOYLE’S, CHARLES’S, GAY-LUSSAC’S AND COMBINED GAS LAWS.
Gases. The Nature of Gases  1. Gases have mass –A car tire weighs more with air in it than it would completely empty.  2. It is easy to compress a gas.
GAS LAWS Boyle’s Charles’ Gay-Lussac’s Combined Gas Ideal Gas Dalton’s Partial Pressure.
Gas Laws Review.
PRACTICE AND REVIEW GAS LAWS. STUDENT LEARNING OBJECTIVES 1.Define pressure. Identify units of pressure and make conversions between appropriate pressure.
Gases. Units of Pressure 1atm. = 760mm Hg (torr) = 101,325 pascals (Pa) = kPa = psi.
AN INTRODUCTION To Gases What is a GAS? Solid Liquid Gas.
The Gas Laws.
Gases Chapter 13.
Gases.
What are the standard conditions (STP) for temperature and pressure?
Complete the following statements.
Gas Laws Chapter 14.
Individual Gas Laws Law of Partial Pressure, combined gas law, boyle’s law, charle’s law, Ideal Gas Law, Molar volume.
Presentation transcript:

CHEMISTRY THE BEHAVIOR OF GASES

VARIABLES THAT DESCRIBE A GAS Compressibility: a measure of how much the volume of matter decreases under pressure. Pressure: a physical force pushing on or against an object; abbreviated P, measured in atmospheres (atm), torr, mmHg, Pascals (Pa), or kilopascals (kPa). Standard pressure (STP) is 1 atm = 760 torr = 760 mmHg = 101,300 Pa = kPa

Volume: the amount of space an object occupies; abbreviated V, measured in liters, milliliters, cubic meters, or cubic centimeters.

Temperature: a measurement of the average kinetic energy in an object; abbreviated T, measured in Celsius or Kelvin (use Kelvin for math problems). Standard temperature (STP) = 0°C = 273 K

Mole: a measurement of the number of particles in an object; abbreviated n, measured in moles. One mole is equal to 6.02 x particles (atoms, molecules, or formula units).

THE GAS LAWS

BOYLE’S LAW FOR PRESSURE-VOLUME CHANGES For a given mass of gas at constant temperature, the volume of the gas varies inversely with pressure. P 1 V 1 = P 2 V 2 orP 1 = V 2 P 2 V 1 You do not need to convert pressure or volume to specific units for these problems because they use ratios.

A gas is collected in a 242 mL container. The pressure of the gas in the container is measured and determined to be 87.6 kPa. What is the volume of this gas at kPa? Assume the temperature is constant. P 1 V 1 = P 2 V 2 P 1 = 87.6 kPa V 1 = 242 mL P 2 = kPa V 2 = ? (87.6)(242) = (101.3)V 2 V 2 = 87.6 * 242 = 209 mL 101.3

CHARLES’ LAW FOR TEMPERATURE- VOLUME CHANGES The volume of a fixed mass of gas is directly proportional to its Kelvin temperature if the pressure is kept constant. V 1 = V 2 orV 1 = T 1 T 1 T 2 V 2 T 2 Temperature must be in Kelvin. K = °C + 273

A sample of gas at 15°C and 1 atm has a volume of 2.58 L. What volume will this gas occupy at 38°C and 1 atm? Assume the pressure is constant. V 1 = V 2 T 1 T 2 V 1 = 2.58 LT 1 = = 288 K V 2 = ? T 2 = = 311 K 2.58 L = V 2 ___ 288 K311 K V 2 = 2.58 L * 311 K 288 K = 2.79 L

GAY-LUSSAC’S LAW FOR TEMPERATURE-PRESSURE CHANGES The pressure of a gas is directly proportional to the Kelvin temperature if the volume is kept constant. P 1 = P 2 orP 1 = T 1 T 1 T 2 P 2 T 2 Temperature must be in Kelvin. K = °C + 273

A 2.0 L flask contains helium gas at a pressure of 685 torr and a temperature of 0°C. If the temperature is raised to 150.°C, what is the new pressure in the flask? P 1 = P 2 T 1 T 2 P 1 = 685 torrT 1 = = 273 K P 2 = ? T 2 = = 423 K 685 torr = P 2 ___ 273 K 423 K P 2 = 685 torr * 423 K 273 K = 1060 torr

THE COMBINED GAS LAW This law combines pressure, volume, and temperature. Temperature must be in Kelvin. K = °C By canceling out any constant terms, we can derive Boyle’s, Charles’, and Gay-Lussac’s law from the combined gas law. Easy way to remember: “ P eas and V egetables on the T able”

If a helium-filled balloon has a volume of 3.40 L at 25.0ºC and kPa, what is its volume at STP? V 1 = 3.40 L T 1 = 25 ºC P 1 = 120 kPa T 2 = 0 ºC P 2 = kPa = 298 K = 273 K V 2 = ? P 1 V 1 P 2 V 2 T 1 T 2 P 1 V 1 T 2 T 1 P 2 V2V2 = = V2V2 =(120 kPa) (3.40 L) (298 K ) (101.3 kPa) (273 K ) V2V2 = 3.69 L

REAL VS. IDEAL GASES Ideal gases follow the gas laws at all conditions of temperature and pressure. They do not exist in reality (for example, real gases can be liquefied and sometimes solidified; ideal gases cannot). Real gases “deviate” from ideal gas behavior. Real gases behave most ideally at high temperature and low pressure.

THE IDEAL GAS LAW The ideal gas law allows us to relate the pressure, volume, number of moles, and temperature of a gas to each other. This law uses the ideal gas constant, R. For the ideal gas law, Pressure must be in atm Volume must be in L n must be moles (it always is) R = L*atm/mol*K T must be in Kelvin

A 5.0 L flask contains 0.60 g O 2 at a temperature of 22ºC. What is the pressure (in atm) inside the flask? PV = nRTP = V = n = R = T = 5.0 L 1 mol O g O g O 2 = mol O 2 ? 22ºC P = nRT V P = = 295 K ( mol)(0.0821)(295 K ) (5.0 L) atm

How many grams of krypton are present in a 600. mL container at 1010ºC in which the pressure of krypton is 10.0 atm? PV = nRT P = V = n = R = T = 1) find moles of Kr 10.0 atm 600. mL ? 1010 ºC+ 273 = 1283 K Solve for n PV RT n = (10.0 atm)(0.600 L) (0.0821)(1283 K ) n = mol Kr = L

mol Kr 83.8 g Kr 1 mol Kr 4.78 g Kr= mol Kr6.02 x atoms Kr 1 mol Kr = 3.43 x atoms Kr 2) Convert to grams How many atoms is this?

GAS MOLECULES: MIXTURES AND MOVEMENTS

AVOGADRO’S HYPOTHESIS Equal volumes of gases at the same temperature and pressure contain equal numbers of particles. At STP, 1 mole of particles of any gas = 22.4 L.

DALTON’S LAW OF PARTIAL PRESSURE At constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures. P total = P 1 + P 2 + P 3 …

Determine the total pressure of a gas mixture that contains nitrogen and oxygen if the partial pressure of the nitrogen is 725 mm Hg and the partial pressure of the oxygen is 426 mm Hg. P total = P 1 + P 2 + P 3 … P total = ? P 1 = P 2 = 725 mm Hg 426 mm Hg P total =725 mm Hg mm Hg P total = 1151 mm Hg

GASES ARE OFTEN COLLECTED BY WATER DISPLACEMENT. The total of the gas pressure plus the water vapor pressure is equal to the atmospheric pressure. P atmospheric = P gas + P H 2 O When we work a problem like this we must always look up and subtract the water vapor pressure to get the gas pressure.

A sample of N 2 gas is collected by the downward displacement of water from an inverted bottle. What is the partial pressure of the N 2 gas at 20.0ºC, if the atmospheric pressure is 752 mm Hg? The water vapor pressure is 17.5 mm Hg at 20.0ºC. P total = P 1 + P 2 + P 3 … P total = P 1 = P N2 752 mm Hg P 2 = P H2O = 17.5 mm Hg = ? 752 mm Hg = P mm Hg P 1 = mm Hg atmospheric P =