IDEAL GASES Flashcards

1
Q
  1. What is the atmosphere composed of?
A
  • Nitrogen (N2)
  • Oxygen (O2)
  • Water Vapour
    (this depends on the local humidity levels)
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2
Q
  1. What are three properties of gases?
A
  1. they are miscible
    (they mix together)
  2. they form homogenous mixtures
  3. they are compressible
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3
Q
  1. Why do water and oil not mix together when they are in a liquid state?
A
  • oil is less dense than water
  • it will rise above the water
  • water is more dense than oil
  • it will sink below the oil
  • they have different intermolecular forces between
    their particles
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4
Q
  1. In which state do oil and water mix together?
A
  • in a gaseous state
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5
Q
  1. What results in the properties of gases?
A
  • the large distances between the gas particles
  • this limits the interactions that are possible between
    the particles
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6
Q
  1. What is air composed of?
A
  • 0.1% volume of gas particles
  • 99.9% empty space
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7
Q
  1. How is gas pressure calculated mathematically?
A
  • it is the force divided by the given area
  • the units of force are Newtons
  • the units of area are m²
  • the units of pressure is Pascals (Pa)
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8
Q
  1. How else can Newtons be written?
A
  • kg m / s²
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9
Q
  1. How else can Pascals (Pa) be written?
A
  • N/m²
  • kg / (ms²)
  • pascals are an extremely small unit
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10
Q
  1. How would we work out the Gas pressure in this diagram?
  • the column of the Earth’s atmosphere has a
    dimension of 1m x 1m
  • this is estimated to have a mass of 10 300kg
  • the column of gases is pressing down on the surface
    of the Earth at sea level
  • this creates the atmospheric pressure
  • the area of the column is 1.00m²
A
  • P = m x g / A
  • the gravitational force is calculated as F = m x g
  • g = Earth’s gravitational constant
  • g = 9.8m.s⎺²

∴P = 10 300 kg x 9.81m.s⎺² / 1.00m²

NB:
- if we go to a high mountain
- the height of the column is smaller
- this gives a reduced mass
- it also gives a reduced atmospheric pressure

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11
Q
  1. Why is Mercury harmful to your health?
A
  • it is neurotoxic
  • it destroys the neurons in oyur brain
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12
Q
  1. What is a Barometer?
A
  • it is a weight measuring device
  • it measures the weight of the atmospheric gases acting
    on the Earth
  • it is a crude instrument
  • it is used for measuring atmospheric pressures
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13
Q
  1. How do we set up a Mercury Barometer?
A
  • we fill up a bowl with liquid mercury
  • we fill a glass test tube completely with mercury
  • we place the glass test tube with the opening facing
    downwards
  • the test tube is placed inside the bowl with Mercury
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14
Q
  1. How does a Mercury Barometer work?
A
  • gravity pulls down on the Mercury in the test-tube
  • the mercury moves down the test tube
  • this creates a vacuum at the top
  • the atmospheric pressure is also pushing down on the
    liquid mercury in the bowl
  • this pushes the liquid up into the test tube
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15
Q
  1. How do we express atmospheric pressure using a Mercury Barometer?
A
  • when a balance is reached between the forces in the
    Mercury barometer
  • the height of Mercury in the test tube is measured
  • in this case it is 760mm
  • this is the atmospheric pressure
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16
Q
  1. What is are other equivalent units of 1 atm?
A
  • 760 mmHg
  • 760 torr
  • 101.325 kPa
17
Q
  1. What is a torr?
A
  • it is a unit of measurement
  • it is equal to 1 mmHg
18
Q
  1. What is one bar equal to?
A
  • 100 kPa
  • 0.986923 atm
19
Q
  1. How do we calculate the pressure of an enclosed gas?
A
  • using an open ended manometer
20
Q
  1. What does an open-end manometer consist of?
A
  • it has a glass bulb on the left side
  • this is filled with an unknown gas
  • it has a U shaped tube
  • the U shaped tube is filled with Mercury
  • the right side of the U-tube is open to the
    atmosphere
21
Q
  1. How does an Open end Manometer work?
A
  • the atmosphere is pushing down on the right side of
    the U-tube
  • this is pushing the Mercury down
  • the gas is pushing down on the mercury on the left
    side of the U-tube
22
Q
  1. What happens when the gas pressure is equal to the atmospheric pressure in the Open End Manometer?
A
  • the levels of the mercury in the two arms of the U-tube
    will be the same
23
Q
  1. What happens when the gas pressure is less than the atmospheric pressure in the Open End Manometer?
A
  • the right side of the U-tube will be lower than the left-
    side
24
Q
  1. What happens when the gas pressure is more than the atmospheric pressure in the Open End Manometer?
A
  • the left side of the U-tube will be lower than the right-
    side
25
Q
  1. What determines the pressure that an enclosed gas exerts?
A
  • the frequency of the collisions with the inner container
    walls
  • the intensity of these collisions
26
Q
  1. What kind of motion do the gas particles inside the box have?
A
  • constant motion
  • this type of motion is random
  • it is called Brownian motion
27
Q
  1. What does the Brownian motion of these particles result in?
A
  • the randomness of the motion results in continuous
    collisions between the gas particles
  • this leads to a redirection of these particles in different
    directions
28
Q
  1. What creates pressure in this container?
A
  • the gas particles collide frequently with the inner
    walls of the container
  • this creates pressure
29
Q
  1. Which two factors determine the magnitude of the pressure inside the box?
A
  1. THE FREQUENCY OF THE COLLISIONS
    • these happen with the inner walls of the box
  2. THE INTENSITY OF THE COLLISIONS
30
Q
  1. What happens when the frequency of the collisions of the particles is higher?
A
  • the higher the pressure within the box will be
31
Q
  1. What happens when the intensity of the collisions of the particles is higher?
A
  • the higher the force of the collision
  • the pressure is higher
32
Q
  1. What keeps a balloon from capsizing on itself?
A
  • the collisions of the particles within the balloon
  • these collisions are caused by the Brownian motion of
    the particles
33
Q
  1. What will happen to the pressure inside a container of gas if the temperature of the gas is increased?
A

A HIGHER TEMPERATURE RESULTS IN:
- the particles moving faster
- the particles have more kinetic energy
- they collide with the walls of the container more
frequently
- they collide with the walls with more force
- the total pressure inside the container increases

34
Q
  1. What will happen to the pressure inside a container of gas if the container is reduced to half its volume?
A

A HALVED CONTAINER RESULTS IN:
- the particles are moving at the same speed
- they will collide with the walls of the container with
the same force
- they will travel a much shorter distance before they
collide with the walls of the container
- they will collide more frequently
- the pressure will increase