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GASES AND THEIR BEHAVIOR

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GASES AND THEIR BEHAVIOR Chapter 5 Properties of Gases Only 4 quantities are needed to define the state of a gas: 1). The quantity of the gas, n (in moles) 2). – PowerPoint PPT presentation

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Title: GASES AND THEIR BEHAVIOR


1
GASES AND THEIR BEHAVIOR
  • Chapter 5

2
Properties of Gases
  • Only 4 quantities are needed to define the state
    of a gas
  • 1). The quantity of the gas, n (in moles)
  • 2). The temperature of the gas, T (Kelvin)
  • 3). The volume of a gas , V (Liters) 1000mL1L
  • 4). The pressure of the gas, P (atmospheres)

3
Gas Pressure
  • A measure of the force that it exerts on its
    container. Force is the physical quantity that
    interferes with inertia. Gravity is the force
    responsible for weight.
  • Force Mass x acceleration, Newtons 2nd law.
  • N kg x m/s2
  • Pressure Force/unit area N/m2

4
  • Barometer invented by Evangelista Torricelli in
    1643. Uses the height of a column of mercury to
    measure gas pressure (especially atmospheric)
  • 1mmHg 1torr
  • 760mmHg 760torr 1atm 101.325kPa
  • 101.325kPa 14.7psi (pounds per square inch)

5
Practice problems
  • 515mmHg in kPa
  • 727mmHg into kPa
  • 52.5kPa into atm

6
Your problems
  • 1. 52.5kPa into atm
  • 2. 0.729atm into mmHg
  • 3. 522torr into kPa
  • 4. 1.10atm into psi
  • 5. 800mmHg into atm
  • 6. 125kPa into torr
  • 7. Rank the following pressures in decreasing
    order of magnitude (largest first, smallest
    last) 75kPa, 300torr, 0.60atm and 350mmHg

7
Gas Laws The experimental basis
  • Boyles law The father of chemistry.
  • His law states the volume of a confined gas is
    inversely proportional to the pressure exerted on
    the gas.
  • Pressure and volume are inversely proportional
  • Temperature is constant
  • For a given quantity of a gas at constant
    temperature, the product of pressure and volume
    is a constant.
  • P1V1 P2V2

8
Example
  • A Sample of carbon dioxide with a pressure of
    55mmHg and a volume of 125mL is placed in a new
    flask. The pressure of the gas in the new flask
    is 78mmHg. What is the volume of the new flask?

9
Charles law
  • If a given quantity of gas is held at a constant
    pressure, then its volume is directly
    proportional to the Absolute temperature. Must
    use Kelvin
  • V1T2V2T1

10
Avogadros Law
  • Avogadros law says that for a gas at constant
    temperature and pressure , the volume is directly
    proportional to the number of moles of gas.
  • V1n2V2n1
  • V1 Initial volume
  • n1 initial number of moles
  • V2 final volume
  • n2 final number of moles

11
  • A 5.20L sample at 18C and 2.00 atm pressure
    contains 0.436 moles of a gas. If we add an
    additional 1.27moles of the gas at the same
    temperature and pressure, what will the total
    volume occupied by the gas be.

12
  • Suppose we have a 12.2L sample containing 0.50mol
    oxygen gas(O2) at a pressure of 1atm and a
    temperature of 25C. If all this 02 were
    converted to ozone at the same temperature and
    pressure, what would be the volume of the ozone?

13
  • Charless Law
  • 1) If I have 45 liters of helium in a balloon at
    250 C and increase the temperature of the balloon
    to 550 C, what will the new volume of the balloon
    be?

14
  • 3) I have 130 liters of gas in a piston at a
    temperature of 2500 C. If I cool the gas until
    the volume decreases to 85 liters, what will
    temperature of the gas be?

15
  • 2) Calcium carbonate decomposes at 12000 C to
    form carbon dioxide and calcium oxide. If 25
    liters of carbon dioxide are collected at 12000
    C, what will the volume of this gas be after it
    cools to 250 C?
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