Chapter 14: Gases Flashcards

1
Q

Gas

A

No definite shape or volume

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2
Q

The atmosphere

A

1) Ocean of air/gases
2) Exerts pressure
3) Competing factors
4) Without the sun, molecules fall to Earth (Earth’s gravity wins)
5) WIthout the Earth’s gravity, molecules fly into space (“Sun wins”)

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3
Q

Competing factors

A

1) Kinetic energy of molecules (Energized by sunlight)
2) Gravity (Pulled down by Earth)

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4
Q

Lived at the bottom of an ocean of air (gases)

A

1) p(liquid) = nearly constant
2) p(atmosphere) = varies a lot

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5
Q

Air becomes less dense with

A

Increasing altitudes (30 km thick atmosphere)

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6
Q

Air is more compressed/dense at sea level than at

A

Higher altitude

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7
Q

Liquid (less pressure)

A

Bottom layer experiences more pressure than the upper layer

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8
Q

Liquid (more pressure)

A

Each layer holds the weight of the previous layers

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9
Q

Atmosphere is divided into 5 layers

A

1) Pressure = Less = Exosphere
2) Pressure = Less = Thermosphere
3) Pressure = Less = Mesosphere
4) Pressure = Less = Stratosphere
5) Pressure = High = Troposphere

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10
Q

Air pressure, like water, acts equally in

A

All directions at a specified height

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11
Q

Just as water pressure is caused by

A

The weight of water

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12
Q

Atmospheric pressure is caused by

A

The weight of air

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13
Q

Air is being pulled down by

A

The gravitational force

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14
Q

Atmosphere pressure varies from

A

One locality to another

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15
Q

Atmosphere pressure surrounded by

A

Air in all directions

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16
Q

Pressure decreases with

A

Increasing altitude

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17
Q

The barometer is a device to

A

Measure atmospheric pressure

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18
Q

Pressure consists of a mercury tube

A

Upside down in a dish filled mercury

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19
Q

Pressure the height of the mercury column tells us

A

The atmospheric pressure

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20
Q

Mercury column exerts pressure on

A

The mercury in the dish

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21
Q

Atmosphere exerts pressure on

A

The mercury in the dish

22
Q

These two pressures must be equal so that

A

The atmospheric pressure supports the mercury column

23
Q

The pressure and volume of a gas enclosed in a space are

A

Inversely proportional

24
Q

Piston

A

A disk or short cylinder that moves up or down against a liquid or gas

25
Q

If you increase pressure, the volume will

A

Decrease by the same factor

26
Q

Boyle’s Law

A

The pressure and volume of a gas enclosed in a space are inversely proportional

27
Q

The product of pressure and volume of a given mass of gas will always

A

Remain the same

28
Q

Buoyancy of Air

A

Archimedes’s principle applies to air as well as liquids

29
Q

An object surrounded by

A

Air is buoyed up by a force equal to the weight of the air displaced

30
Q

Rule for “Lighter than air” objects

A

1) When the weight of air displaced by an object is greater than the weight of the object, it rises
2) When the weight of air displaced by an object equals the weight of the object, it hovers in air
3) When the weight of air displaced by an object is less than the weight of the object, it is supported by air

31
Q

1) When the weight of air displaced by an object is greater than the weight of the object, it rises

A

W(ob) < W(disp)

32
Q

2) When the weight of air displaced by an object equals the weight of the object, it hovers in air

A

W(ob) = W(disp)

33
Q

3) When the weight of air displaced by an object is less than the weight of the object, it is supported by air

A

W(ob) > W(disp)

34
Q

Gas filled balloons

A

Buoyancy with hydrogen, the lightest gas (flammable seldom used) and next best buoyancy with helium

35
Q

As balloons rise, atmosphere becomes

A

Less dense since pressure decreases, volume increases then the balloon expands

36
Q

Gas-filled balloon will continue to rise until the weight of displaced air equals

A

The total weight of the balloon

37
Q

The buoyant force on the balloon equals

A

Its weight which says the same thing

38
Q

Bernoulli’s Principle

A

Where the speed of a fluid increases, internal pressure in the fluid decreases (and vice versa)

39
Q

Bernoulli’s Principle applies to a smooth, steady flow

A

1) Mainly applied to incompressible fluids
2) Fluid with constant density

40
Q

Bernoulli’s Principle farther apart

A

1) Flow speed is less
2) Pressure within the fluid is greater

41
Q

Bernoulli’s Principle closer apart

A

1) Flow speed is greater
2) Pressure within the fluid is less

42
Q

Applications of Bernoulli’s Principle

A

1) Blow on the top surface of a paper and the paper rises
2) Reasons: Pressure of the moving air is less than the atmospheric pressure beneath it

43
Q

Wind blowing above and below an airplane wing produces lift

A

Reasons: Air velocity is greater over the top of the wing than the bottom. Pressure is greater at the bottom and produces lift

44
Q

Plasma

A

An electrified gas

45
Q

Atom in a plasma are

A

Ionized and stripped of one or more electrons, with a corresponding number of tree electrons

46
Q

Sun and other stars contain

A

Plasma

47
Q

Aurora borealis and the aurora australis are

A

Glowing plasma in the upper atmosphere

48
Q

Fluorescent lamps and neon signs - When a lamp is turned on, a high voltage between electrodes of the tube causes

A

Electron to flow

49
Q

Electrons ionize some atoms

A

Forming plasma

50
Q

Plasma provide a conducting path that

A

Keeps the current flowing

51
Q

Radiations causes the phosphor coating on the tube’s inner surface to glow with

A

The visible light