chapter 8: Gases Flashcards

1
Q

what are the percentages of gases in the air

A
N2 = 78
O2 = 21
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2
Q

the air we breathe is a…

A

mixture of gases

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3
Q

what are some characteristics of gases

A
  • Spontaneously expand to fill their containers (no outside energy)
  • highly compressible
  • homogenous mixture
  • low density
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4
Q

what happens when the gas particles collide with each other

A

creates pressure

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5
Q

what is pressure

A

force that results from the collisions
of gas particles divided by the area of the surface
with which they collide

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6
Q

what is the formula for pressure

A
P = F/A
force = m x a
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7
Q

what does pressure depend on

A

of gas particles

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8
Q

fewer gas particles =

A

lower pressue

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9
Q

how does altitude affect pressure

A

pressure decreases above 30 k

- keep cabins pressurized

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10
Q

how does gravity affect the atomosphere

A

causes the atmosphere as a whole to press down on earth

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11
Q

what is atmospheric pressure

A

weight of air per unit of area

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12
Q

what is the si unit for force

A

newton (N)

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13
Q

what is the SI unit of pressure

A

N/m^2 or pascal (Pa)

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14
Q

who was pascal named after

A

Blaise Pascal

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15
Q

what is bar

A

used to report pressure; 10^5 Pa

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16
Q

who discovered atm,torr, mmhg

A

evangelista torricelli ( Galileo’s student)

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17
Q

who invented the mercury barometer

A

torricellu

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18
Q

what is standard atomospheric pressure

A

pressure @ sea lvl

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19
Q

what is the standard atms. press.

A

101325 Pa or 101.325 kPa

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20
Q

what non si units are w/ the atmospheric pressure

A

atm, mmhg m torr

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21
Q

what is a mamometer

A

measure pressure of enclosed gases

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22
Q

what did robert boyle do

A

investigated the relationship between the pressure

of a gas and its volume.

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23
Q

what was boyle’s law

A

volume and pressure are inverse @ constant temp

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24
Q

boyle’s law formula

A

P1V1 = P2V2

25
Q

what did jacques charles do

A

discovered relationship between volume and temp

26
Q

what was charles law

A

volume and temp are proportional @ maintained pressure

27
Q

charles law formula

A

V1/T1 = V2/T2

28
Q

what did gay lussac do and who was he

A

discovered relationship between gas and volume

law of combining volumes

29
Q

what is the law of combining volumes

A

given P and T, the Vs of gases that react with
one another are in the ratios of small whole numbers
example: wo volumes of H2 gas react with one volume
of O2 gas to form two volumes of water vapor.

30
Q

avogadro’s hypothesis

A

equal volumes of gases at the same temp and pressure have equal # of molecules

31
Q

what are stp conditions

A

22.4 L
0 degrees celcius
1 atm

32
Q

22.4 L =

A

6.022 x 10^23 molecules = 1 mol

33
Q

avogadro’s law

A

volume is directly proportional to # of moles

(temp, pressure = constant_

34
Q

what is the ideal gas equation

A

pv = nrt

35
Q

what is an ideal gas

A

hypothetical gas whose pressure,
volume, and temperature behavior is completely
described by the ideal-gas equation.

36
Q

what does R = in pvnrt

A

0.08206 L-atm/mol K

37
Q

avogadro’s law formula

A

V1/n1 = V2/n2

38
Q

pressure volume and temp formula

A

P1V1/T1 = P2V2/T2

39
Q

what is the formula for density

A

d = m/V

40
Q

moles per unit of volume =

A

P /RT

41
Q

what is the formula for partial pressure

A

P = n1RT/V

42
Q

what does p total =

A

RT/V

43
Q

mole fraction x

A

n1/ntotal

P1 = (n1/ntotal)Ptotal = X1Ptotal

44
Q

how is gas collected

A

through water displacement

45
Q

what does vapor pressure depend on

A

temp

46
Q

what does the ideal gas law show and what does it lack

A

how gases behave but doesn’t explain why they behave like that

47
Q

kinetic molecular theory describes…

A

model to help us picture what
happens to gas particles as
experimental conditions change.

48
Q

what is the kinetic molecular theory

A
  1. ) volume = zero
  2. ) particles in constant motion
  3. ) particles have no force
49
Q

gases in the same container have the same temp….

A

have the same average kinetic enegy

50
Q

lighter particles =

A

faster average velocity

51
Q

as temp increases

A

average velocity increases

52
Q

what is diffusion

A

spread of a substance throuhout a space or second substance

53
Q

what direction do gas molecules travel in

A

straight line

54
Q

mean free path

A

avg distance a molecule travels between collisions

55
Q

mean free path decreases as

A

pressure increases
Black Friday = Crowded = high pressure = short distance
before bumping into someone = short mean free path
‒ Mall after closing = low pressure = long distance before
bumping into someone = long mean free path

56
Q

effusion

A

escape of gas molecule through tiny hole

57
Q

characteristics of ideal gas law

A
  • no attraction between has molecules

- gas molecules do not take up space

58
Q

what conditions are ideal gas laws valid in

A

high temp low pressure

59
Q

what is van de waals equation

A

n^2a/ V2