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Properties of Gases CHAPTER 11 Chemistry: The Molecular Nature of Matter, 6 th edition By Jesperson , Brady, & Hyslop. CHAPTER 11 Learning Objectives. Describe properties of a gas Read a barometer & monometer Unit conversions for moles, temperature, pressure, and volume

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Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Properties of Gases

CHAPTER 11

Chemistry: The Molecular Nature of Matter, 6th edition

By Jesperson, Brady, & Hyslop


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

CHAPTER 11 Learning Objectives

  • Describe properties of a gas

  • Read a barometer & monometer

  • Unit conversions for moles, temperature, pressure, and volume

  • Explain relationships between variables of state & predict effect of a change to a system

  • Apply gas law to stoichiometry, molecular weight, and density problems

  • Understand the relationship between variables of state in terms of Kinetic Molecular Theory

  • Calculate mole fractions and partial pressures

  • Compare rates of effusion

  • Compute variables of state using the real gas law


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

CHAPTER 11 Lecture Road Map

What is a gas?

Define & measure variables of state

Relationships between variables of state

Equation of state for an ideal gas

Dalton’s law of partial pressure & gas stoichiometry

Kinetic Molecular Theory & Graham’s law

Real gas law


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Guy-Lussacs

Law

Charles Law

Avagadro’s

Law

Boyles Law

Mole Fraction

& Mole %

Ideal Gas Law

Dalton’s Law

Volume

CHAPTER 11

Properties of Gases

Real Gas Law

Pressure:

Barometers & Monometers

Pressure

Variables of State

Kinetic Molecular Theory

Temperature:

K, °C, °F

Graham’s Law

Relationships between variables of state

Absolute 0


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

In groups of 3-5 brainstorm how to describe a gas.

What are some observable properties?

What variables would you use to describe a gas?


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

  • Describe a gas:

  • Will expand to fill a volume

  • Mostly empty space so can be compressed

  • Can expand & contract with temperature

  • Particles constantly in motion & constantly colliding

  • Some gases are heavier then others and sink to the floor rather then rise to the ceiling


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Physical Properties of Gases

Despite wide differences in chemical properties, all gases more or less obey the same set of physicalproperties

  • Pressure (P )

  • Volume (V )

  • Temperature (T )

  • Amount = moles (n)

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Volume (V)

V = l × w × h for a cube

V = (4/3) π r3 for a sphere

V = π r2 h for a cylinder

Units of Volume: Liters (L)

1 L = 0.001 m3

= 1000 cm3

= 1000 mL


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

# of Moles (n)

Avagadro’s number (NA) allows us to measure the number of particles of a gas as the number of moles:

NA = 6.02214129 × 1023 particles/mole

We can measure the number of moles of a gas by measuring its mass and knowing its Molar Mass

Molar Mass = mass / (# of moles)

M = m/n

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

  • How many moles of the CFC pollutant CCl2F2 are in 50.0g?


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

Calculate the mass of 3 moles of nerve agent VX:

CH3CH2


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Temperature (T)

Temperature is measured with a thermometer usually in °C, °F, or Kelvin.

0°C = 273 K

1°C = (1°F -32) × (5/9)


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

If Room Temperature (RT) is 25°C,

what is RT in Kelvin? °F?

Write out a formula to convert °F to K.


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

If Room Temperature (RT) is 25°C,

what is RT in Kelvin? °F?

RT = 25°C + 273 K = 298 K


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Pressure (P)

Force = mass × area

  • Pressure is the force of the collisions of the gas distributed over the surface area of the container walls

  • Earth exerts gravitational force on everything with mass near it

  • Atmospheric Pressure of earth: gravity pulling on gases creating a blanket around earth

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

  • Calculate Atmospheric Pressure on Earth.

    • Identify information needed

    • Research

    • Solve


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

Calculate Atmospheric Pressure on Earth.


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Pressure (P)

A vacuum exerts zero pressure on a containers walls.

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Pressure (P)

Measure Atmospheric pressure with a barometer.

ToricelliBarometer:

  • Tube that is 80 cm in length

  • Sealed at one end

  • Filled with mercury

  • In dish filled with mercury

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Pressure (P)

  • Atmospheric pressure

    • Pushes down on mercury

    • Forces mercury up tube

  • Weight of mercury in tube

    • Pushes down on mercury in dish

  • When two forces balance

    • Mercury level stabilizes

    • Read atmospheric pressure

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Pressure (P)

  • If atmospheric pressure is high

    • Pushes down on mercury in dish & increase level in tube

  • If atmospheric pressure is low

    • Pressure on mercury in dish less than pressure from column & decreaselevel in tube

      Therefore:

  • Height of mercury in tube is the atmospheric pressure

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Pressure (P)

  • measured with a barometer

  • P=g×d×h

    • d=density of the liquid

    • g= gravitational acceleration

    • h=height of the column supported

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Pressure (P)

Typical range of pressure for most places where people live

730 to 760 mm Hg

Top of Mt. Everest

Atmospheric Pressure = 250 mm Hg

Standard Atmosphere (atm)

Average pressure at sea level

Pressure needed to support column of mercury 760 mm high measured at 0 °C = 1 atm

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Pressure (P)

SI unit for pressure

Pascal = Pa = 1 N/m2

1atm = 101,325 Pa = 101 kPa

100 kPa = 0.9868 atm

Other units of pressure

1.013 Bar = 1013 mBar = 1 atm

760 mm Hg = 1 atm

760 torr = 1 atm

At sea level 1 torr = 1 mm Hg

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

Express Pressure in atm and kPa for a gas at 705 mmHg.


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Variables of State

Pressure (P)

Open Ended Manometer

Pgas > Patm

Gas pushes mercury

uptube

Pgas < Patm

Atmosphere pushes mercury downtube

Pgas = Patm

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

CO2 collected in a monometer in a lab with a barometric reading of 97 kPa. What is the Pressure of CO2?

33 mm


Closed end manometer

Variables of State

Closed-end Manometer

Pressure (P)

  • Arm farthest from vessel (gas) sealed

  • Tube filled with mercury

  • Then open system to flask and some mercury drains out of sealed arm

  • Vacuum exists above mercury in sealed arm

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Closed end manometer1

Variables of State

Closed-end Manometer

Pressure (P)

  • Level of mercury in arm falls, as not enough pressure in the flask to hold up Hg

  • Patm = 0

  • Pgas = PHg

  • So directly read pressure

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

What is the pressure of an unknown gas within this closed monometer?

Closed monometer

437 mm

205 mm


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Ideal Gas Law

Boyle’s Law

Volume will change to equalize pressure with atmosphere is not in a rigid vessel.

V α 1/P

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Ideal Gas Law

Charles Law

If Pressure is constant but freeze a balloon, it decreases in V

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Ideal Gas Law

Charles Law

If Pressure is constant but freeze a balloon, it decreases in V

V α T

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Low T, Low P

P

High T, High P

T (K)

Ideal Gas Law

Gay Lussac’s Law

Volume (V ) and number of moles (n) are constant

P increases as T increases

Showed that gas pressure is directly proportional to absolute temperature

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

What happens to gas pressure when you raise the temperature?

Pressure increases because the faster moving molecules hit the walls of the container with greater force

No change in pressure is observed because the area increased.


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Ideal Gas Law

Combined Gas Law

  • Boyle’s law:

  • Charles Law:

  • Guy-Lussac’s Law:

  • is equivalent to

  • For any two conditions:

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Ideal Gas Law

Combined Gas Law

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

N2 + H2 NH3

How much H2 at 0°C and 0.86 atm do you need to react completely with 750 mL of N2 at 1.5 atm and 20°C to form ammonia?

What is the number of moles of ammonium produced if the density of hydrogen is 0.08988 g/L?

Hint: is this equation balanced?


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

A sample of helium gas occupies 500.0 mL at 1.21 atm Calculate the volume of the gas if the pressure is reduced to 491 torr


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Ideal Gas Law

Avagadro’s Law

V α n

At standard temperature (273 K)

And standard pressure (1 atm)

1 mole of any gas will occupy the same volume

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

What happens to gas pressure when you increase the number of molecules in the container?

pressure increases because more molecules hit the walls of the container, thus exert a greater force on the container

No pressure change is observed.


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Ideal Gas Law

Putting It All Together

Ifthen

  • R is the universal gas constant

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

Plug in values of T, V, n and P for 1 mole of gas at STP (1 atm and 0.0 °C)

T = 0.0 °C = 273.15 K

P = 1 atm

V = 22.4 L

n = 1 mol

R = 0.082057 L atmmol–1 K–1


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Ideal Gas Law

Putting It All Together

Ifthen

  • R is the universal gas constant

  • R = 0.0821 (L×atm) / (mol×K)

  • = 8.314 J / (mol×K)

  • = 8.314 (kg×m2) / (s2×mol×K)

  • PV = nRT

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

Calculate Molar Volume = the volume 1 mole of any gas occupies at 1 atm and 273 K


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

Compare Molar volume at STP to Room Temperature(25°C) assuming pressure remains constant


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

How many liters of N2(g) at 1.00 atm and 25.0 °C are produced by the decomposition of 150. g of NaN3?

2NaN3(s)  2Na(s) + 3N2(g)


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

At what temperature will 1.50 moles of CH4 occupy a 1 L container at 10atm?


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

  • PV = nRT

  • d = m / V

  • M = m / n

  • Write out the ideal gas law in terms of density & then in terms of molar mass


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Ideal Gas Law

Considering Density & Molar Mass

  • PV = nRT

  • d = m / V

  • M = m / n

  • P (m / d) = nRT

  • PV = (m / M) RT

  • RT / P = M / d

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

At what temperature will 479.4 g of Br2 occupy a 1 L container at 25 atm?


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

2H2O (l) + catalyst + hv 2H2 (g) + O2 (g)

Under the following conditions if 40.53 g of a 1 L Volume of water is split into hydrogen and oxygen gas, what is the volume the gas mixture if collected in a balloon (ignore water vapor)?

T = 25°C

Patm = 1.025 atm

dH2O = 1 g/mL

mH2O = 40.53 g


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Dalton’s Law

Partial Pressure

For mixture of non-reacting gases in container

Total pressure exerted is sum of the individual partial pressures that each gas would exert alone

Ptotal = Pa + Pb + Pc + ···

Where Pa, Pb, and Pc are the partial pressures

Partial pressure

Pressure that particular gas would exert if it were alone in container

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Dalton’s Law

Partial Pressure

Assuming each gas behaves ideally partial pressure of each gas can be calculated from ideal gas law

So total pressure is

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Dalton’s Law

Partial Pressure

Rearranging

Or

Where ntotal = na + nb + nc + ···

ntotal= sum of number moles of various gases in mixture

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

2H2O (l) + catalyst + hv 2H2 (g) + O2 (g)

With an excess of water (1L) we know that 40.53 g (or 2.25 moles) of water will split. what is the partial pressure of H2 gas and the partial pressure of O2 gas if it is collected in a 25L rigid container (ignore water vapor & change in water volume).

T = 25°C

Patm = 1.025 atm

dH2O = 1 g/mL

VH2Ototal = 1L

Vcontainer = 25L

nH2O = 2.25 moles


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Dalton’s Law

Vapor Pressure

Collected gas pressure must be corrected for water vapor

Ptotal=Pgas + Vpwater


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

32.5 mL of Hydrogen gas is collected over water at 25 ºC and 755 torr. What is the pressure of dry hydrogen gas? (VP25ºC =  23.76 mmHg)

  • Correct Pt to find the Pdry gas:

    • 755-23.76 torr=731.24torr

731 torr = Phydrogen


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

2H2O (l) + catalyst + hv 2H2 (g) + O2 (g)

Continuing the previous problem, what is the total pressure of the system if we include water vapor pressure (still ignoring change in volume of water)?

T = 25°C

Patm = 1.025 atm

dH2O = 1 g/mL

VH2Ototal = 1L

Vcontainer = 1.25L

mH2O = 40.53 g (that reacts)


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Dalton’s Law

Mole Fraction

Mole Fraction (χ)

Ratio of number moles of given component in mixture to total number moles in mixture

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

2H2O (l) + catalyst + hv 2H2 (g) + O2 (g)

Continuing the previous problem, what is mole fraction of water vapor in the system?

T = 25°C

Patm = 1.025 atm

dH2O = 1 g/mL

VH2Ototal = 1L

Vcontainer = 1.25L

mH2O = 40.53 g (that reacts)


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Dalton’s Law

Mole Fraction

  • If V and T are constant then, = constant

  • For mixture of gases in one container

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Dalton’s Law

Mole Fraction

cancels, leaving

or

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Dalton’s Law

Mole Fraction

  • Partial pressure of particular component of gaseous mixture

  • Equals mole fraction of that component times total pressure

Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

Group

Problem

The total pressure of a 1 L container of a room 298K gas mixture is 628 torr. What is the pressure of Cl2 if there are 20 mg of CO2 and 8 mg of Cl2?


Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

  • Small Group Problems:

  • 22.4 L of He at 25 ºC are heated to 200.ºC. What is the resulting volume?

  • A sample of fluorine gas occupies 275 mL at 945 torr and 72 ºC. What is the mass of the sample?

  • What is the density of NO2 at 200 ˚C and 600. torr?

  • What is the molar mass of a gas with a density of 6.7 g/L at -73.ºC and a pressure of 2.49 atm?

  • A sample of oxygen gas occupies 500.0 mL at 722 torr and –25 ºC. Calculate the temperature in ºC if the gas has a volume of 2.53 L at 491 mm Hg.

  • What is the molar mass of a sample of gas if 2.22 g occupies a volume of 5.0 L a 35 ºC and 769 mm Hg?

    • a.1.3 g/mol

    • b.0.015 g/mol

    • c.0.090 g/mol

    • d. None of these

  • What is the mole fraction of N2 in the atmosphere? 1.000atm Air = .7808 atm N2+ .2095 atm O2+ .0093 atmAr + .00036 atm CO2

  • Pump 520 mm Hg N2 and 250 mm Hg O2 into an empty gas cylinder. What is the overall pressure of the mixture?


  • Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    5 Assumptions

    Gas particles are tiny, their V is negligible.

    Particles travel in a straight line, in random directions.

    0 intermolecular attraction.

    Elastic collisions, no Energy is lost.

    If KE α T, then assume average KE α T.

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Group

    Problem

    • Compare to observations from beginning of class.

    • Describe the relationships of state variables in terms of Kinetic Molecular Theory:

      • P α 1 / V

      • P α T

      • V α T

      • V α n


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Boyle’s Law

    Boyles Law

    • Decrease inV, means gas particles hit wall more often

    • IncreaseP

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Guy-Lussac’s Law

    Guy-Lussac’s Law

    • As Tincreases

    • KEaveincrease

    • Speeds of molecules increases

    • Gas particles hit wall more often as V same

    • So P increase

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Charles Law

    Charles Law:

    • As Tincreases

    • KEaveincreases

    • Speeds of molecules increases

    • Gas particles hit wall more often as pressure remains the same

    • So volume increases

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Avagadro’s Law

    • For ideal gas at constant T and P

    • V is directly proportional to n

    • Kinetic Theory of Gases account for this

      • As the number of moles of gas particles increase at same T

      • Holding T and P constant

      • Must V must increase

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Dalton’s Theory

    • Expected from kinetic theory of gases

      • All gas particles are independent of each other

      • Volume of individual particles is unimportant

      • Identities of gases do not matter

    • Conversely, can think of Dalton's Law of Partial Pressures as evidence for kinetic theory of gases

      • Gas particles move in straight lines, neither attracting nor repelling each other

      • Particles act independently

        • Only way for Dalton's Law to be valid

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Absolute 0

    • If KEave = 0, then T must = 0.

    • Only way for KEave = 0, is if v = 0 since m 0.

    • When gas molecules stop moving, then gas as cold as it can get

    • Absolute zero

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Derivation of PV = nRT &

    • Important equations:

    • PV = nRT

    • KE = (3/2) RT

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Graham’s Law of Effusion

    EffusionDiffusion

    Gas mixing through VacuumGases mixing

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Derivation of Graham’s Law of Effusion

    • We can describe how fast a gas will effuse

    • Some Important Equations:

    • ūrms =√(3RT) / M

    • (ūrms)A /(ūrms)B = √(MB /MA)

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Kinetic Molecular Theory

    Graham’s Law of Effusion

    (constant P and T)

    And dAMM (constant V and n)

    Therefore, heavier gases effuse slower then lighter gases

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Group

    Problem

    H2O

    CO2

    1 m

    Which gas will travel the farthest? How far will the CO2 travel down the tube before meeting the gaseous water?


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Real Gas Law

    Review Assumptions

    Gas particles are tiny, their V is negligible.

    Particles travel in a straight line, in random directions.

    0 intermolecular attraction.

    Elastic collisions, no Energy is lost.

    If KE α T, then assume average KE α T.

    Real gases do not obey the ideal gas law!


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Real Gas Law

    Experimental Data

    • Gas molecules have finite volumes

      • They take up space

      • Less space of kinetic motions

      • Vmotions < Vcontainer

      • Particles hit walls of container more often

      • Pressure is higher compared to ideal

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Real Gas Law

    Experimental Data

    • D

    • Particles do attract each other

      • Even weak attractions means they hit walls of container less often

      • Therefore, pressure is less than ideal gas

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Real Gas Law

    Experimental Data

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Real Gas Law

    Review Assumptions

    Gas particles are tiny, their V is negligible.

    Particles travel in a straight line, in random directions.

    0 intermolecular attraction.

    Elastic collisions, no Energy is lost.

    If KE α T, then assume average KE α T.

    • Gas particles do take up Volume:

      • Vmeas – nb

    • Attractive forces between molecules exist and effect a particle’s path.

      • Pmeas + [(n2a) / V2]


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Real Gas Law

    Van Der Waal’s Equation for Real Gases

    corrected P corrected V

    • a and b are van der Waal's constants

    • Obtained by measuring P, V, and T for real gases over wide range of conditions

    • Table X.X. in your textbook.

    Jesperson, Brady, Hyslop. Chemistry: The Molecular Nature of Matter, 6E


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Group

    Problem

    Use the Real Gas Law to calculate the Vapor Pressure of 1 mole water in a 1 Liter container at the following Temperatures:


    Properties of gases chapter 11 chemistry the molecular nature of matter 6 th edition

    Guy-Lussacs

    Law

    Charles Law

    Avagadro’s

    Law

    Boyles Law

    Mole Fraction

    & Mole %

    Ideal Gas Law

    Dalton’s Law

    Volume

    CHAPTER 11

    Properties of Gases

    Real Gas Law

    Pressure:

    Barometers & Monometers

    Pressure

    Variables of State

    Kinetic Molecular Theory

    Temperature:

    K, °C, °F

    Graham’s Law

    Relationships between variables of state

    Absolute 0


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