Chapter 6: the gaseous state Flashcards Preview

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Flashcards in Chapter 6: the gaseous state Deck (157):
1

gases have similar .., which allows us to develop models to predict their ...

physical behaviors; properties

2

a gas is a fluid with no definite ... or fixed ...

shape; volume

3

a gas fills the

total volume of its container

4

because a gas is mostly empty space, a gas is

compressible

5

the volume of a gas ... when an external force is applied

decreases

6

a liquid is a fluid with a

fixed volume but no definite shape

7

a liquid takes the ...., but it does not...

shape of its container; expand to fill the container

8

a solid has both fixed ... and ...

shape; volume

9

liquids and solids are ...

condensed phases

10

condensed phases: phases that are resistant to ... because the spaces between the particles are ... and cannot ....

volume changes; small; readily change

11

because the individual particles in both the liquid and solid phases are ...., but in the gas phase are ..., the density of the gas phase is much ... than the density of either of the condensed phases

closely packed; separated; lower

12

density is generally expressed in .. for a gas, but the densities of liquids and solids are expressed in ...

grams per liter; grams per milliliter

13

when a gas under atmospheric conditions condenses to a solid or a liquid, the density increases by a fact of about

1000

14

liquids and solids are resistant to volume changes because the spaces between the particles are

small and cannot readily change

15

pressure is defined as the

force exerted on a surface divided by the area of the surface

16

the atmosphere exerts a pressure because of the

weight of the gas molecules in the air

17

a barometer measures the

pressure of the amosphere

18

gravitational attraction pulls down the column of mercury, leaving a ... above it in the tube. the column stops falling when the pressure caused by the weight of the mercury is

vacuum; equal to the pressure exerted by the atmosphere

19

mercury level in barometer rises→

high pressure

20

mercury level in barometer lowers→

low pressure

21

mercury is used in barometers because it is a liquid with a

high density

22

a manometer measures pressure

differences

23

(manometer) the atmosphere exerts a ... on the mercury surface at the open end of the tube, and the gas within the container exerts pressure on the ...

pressure; other surface of the mercury

24

(manometer) the difference between the heights of the 2 mercury surfaces corresponds to the difference between the

gas pressure in the container and the atmospheric pressure

25

for a closed-end manometer the pressure of the gas is ... to the difference between the heights of the ...

equal; two mercury surfaces

26

si unit for pressure

pascal

27

1 pa = 1 N/ m^2 =

1 kg/ m * s^2

28

1 bar =

10^5 Pa

29

1 atm= ... mm Hg

760

30

1 torr = ... Pa

133.3

31

1 atm= ... torr

760

32

1 atm= ... psi

14.7

33

psi is

pounds per square inch

34

1 atm= ... kPa

101.325

35

1 atm= ... bar

1.01325

36

1 atm= .... in Hg

29.92

37

the physical properties of all gases behave in the ..., regardless of the ...

same general manner; identity of the gas

38

4 independent properties that define the physical state of a gas:

pressure; volume; temperature; number of moles

39

gas laws express the relationships between the

4 independent properties of gases

40

volume of a gas increases as pressure

decreases

41

boyle's law states that at constant ..., the ... of a sample of gas is ... proportional to the ...

temperature; volume; inversely; pressure

42

V=

constant X 1/P

43

PV=

constant

44

P1V1=

P2V2

45

doubling the temperature causes the volume of the gas to

double

46

charles's law states that at constant ..., the ... of a fixed amount of gas is ... to the absolute ...

pressure; volume; directly proportional; temperature

47

V = (charles's law)

constant * T

48

at absolute zero the volume of the gas must be

zero

49

at absolute zero the volume of gas is zero because all gases .... before they reach this temperature

condense to liquid/solid phase

50

absolute zero: ... degrees C; ... K

-273.15; 0

51

V/T =

constant

52

V1/T1=

V2/T2

53

avogadro proposed that at thes ame temperature and pressure, equal volumes of gases contain the

same number of particles

54

avogadro;s law states that at constant pressure and temperature, the volume of a gas sample is ...

proportional to the number of moles of gas present

55

(avogadro's law) V=

constant * n

56

V1/n1 =

V2/n2

57

combined gas law:

P1V1/n1 = P2V2/n2

58

temps must be expressed in

kelvins

59

R with units L*atm/ mol*K

0.08206

60

R with units kg*m^2/s^2*mol*K

8.314

61

R with units J/mol*K

8.314

62

R with units cal/mol*K

1.987

63

SCUBA:

self-contained underwater breathing apparatus

64

high pressures caused by water at depths greater than ... starts to force more nitrogen gas to .... leading to a state of motor function loss, decision making inability, and impairment in judgment known as ...

50 m; dissolve into the bloodstream and other tissues; nitrogen narcosis

65

the bends: a diver ascends toward the surface too quickly and nitrogen .... which then collect in the ... causing extreme pain and the body ...

bubbles come out of the body tissues; joints; curls up

66

reaction in air bags

decomposition of sodium azide

67

divers use an air mix that contains a lot of ... gas, because helium doesn't ...

helium; dissolve in body tissues to a large extent

68

divers can also use air mixes that contain ..., but this can cause ..., which thus results in uncontrollable ...

heliox; high-pressure nervous syndrome; shaking

69

trimix: mixture of ... o2, ... n2, and ... He

10%; 20%; 70%

70

ideal gas law:

PV=nRT

71

R is the

ideal gas constant

72

the value of the constant R is determined

experimentally

73

measurements show that the volume of 1 mol of an ideal gas at standard temperature and pressure is

22.41 L

74

standard temperature and pressure:

1 atm; 0 degrees C/273K

75

the ideal gas law expresses the interrelationships of

volume, pressure, amount, and temperature

76

we use the term ideal because under certain conditions the behavior of gases

deviates from that predicted by the ideal gas law

77

the idea gas law is used to determine the value of any of the four properties--...., given values of the other three

pressure, volume, amount, and temperature of a gas

78

before the development of mass spectrometry, the molar masses of many substances were determined by using the

ideal gas law

79

the ... of any given gas under a fixed set of conditions is also calculated from the ideal gas law

density

80

at constant pressure and temperature, the density of a gas is directly related to its

molar mass

81

just as in solution, reacting species in the gas phase can readily ..., a necessary requireent for reactions to occur

collide

82

use the ideal gas law to convert the moles of a gas sample to its

equivalent volume

83

in chemical reactions at constant temp and pressure, the volumes of gases combine in the

same proportions as the coefficients of the equation

84

we can directly calculate the volume of a gas produced b a reaction of gases in a chemical reaction, as long as the

pressure and temperaure of the gases are the same

85

we do not need a pue sample of gas to use the

ideal gas law

86

many of the early experiments that led to the formulation of the gas laws were performed with samples of

air rather than pure substances

87

In 1801, English scientist John dalton realized that each gas in a mixture of gases exerts a pressure, called a ..., which is the same as if the gas...

Partial pressure; occupied the container by itself

88

Dalton's law of partial pressure:

Pt = Pa + Pb

89

A mixture of gases is a

Solution

90

A convenient concentration unit to describe this gaseous mixture is the

Mole fraction

91

Mole fraction: the number of moles of one component of a mixture divided by

The total number of moles of all substances present in the mixture

92

χa =

Moles of component A/ total moles of all substances

93

χa=

nA/ ntotal

94

χa+χb+χc+....+χn=

1

95

Pa =

χa x Pt

96

chemists measure the volume of a gas generated in a reaction by

determining the volume of water displaced

97

the gas sample collected by displacement of water is not pure, because some

water molecules are also present in the gas phase

98

the partial pressure of water present in the gas phase depends on the

temperature of the water

99

to determine the partial pressure of the gas collected, you must subtract the partial pressure of the water vapor from the

total pressure

100

scientists made measurements of volumes and temperatures of gases to show that the volume of a gas at constant pressure is

proportional to its temperature in kelvins

101

chemists sought to understand why a single law can describe the physical behavior of

all gases, regardless of the nature/size of the gas particles

102

kinetic molecular theory describes the

behavior of gas particles at the molecular level

103

(4 postulates of kinetic theory) a gas consists of ... that are in ... and .... no .... exist between any two gas particles

small particles; constant; random motion; forces of attraction or repulsion

104

(4 postulates of kinetic theory) gas particles are very ... compared with the ....

small; average distance that separates them

105

(4 postulates of kinetic theory) collisions of gas particles with ... and with the .... are ...

each other; walls of the container; elastic

106

(4 postulates of kinetic theory) elastic: no loss in ... when ...

total kinetic energy; particles collide

107

(4 postulates of kinetic theory) the average kinetic energy of gas particles is proportional to the

temperature on the kelvin scale

108

(kinetic molecular theory) the particles occupy only a small part of the ....; most of the ... is ...

volume of the container; volume; empty space

109

(kinetic molecular theory) the gas particles are in

constant motion

110

(kinetic molecular theory) the ... and ... of the particles change when they collide, but the ... does not change

direction; speed; total energy of the gas

111

(kinetic molecular theory) the energy of the gas changes only if the

temperature changes

112

(kinetic molecular theory) the kinetic molecular theory assumes that the pressure exerted by a gas comes from the

collisions of the individual gas particles with the walls of the container

113

(kinetic molecular theory) pressure increases if the ... or .... increases, because both will increase the ... on the wall

energy of the collisions; the number of wall collisions per second; force

114

the kinetic molecular theory is consistent with the

ideal gas law

115

as the size of a container decreases (at constant temperature), the number of ... of the gas particles with the .... during any time interval ..., because the particles have less ... between collisions with the walls

collisions; walls per unit area; increases; distance to travel

116

at constant temperature, the average force of each collision ..., but in a smaller volume, the same number of particles strike a given area of the wall ..., so the pressure of gas in the container ...

does not change; more often; increases as volume decreases

117

with an increase in temp and thus an increase in kinetic energy, each collision exerts a ..., and the number of collisions per unit area per time ...

greater force on the walls; increasese

118

if pressure is to remain constant, the size of the container must ..., reducing the number of these more ...

increase; energetic collisions per unit area

119

increasing the number of gas particles in a container increases the

number of collisions with the walls per unit area per unit time

120

not all gas particles move at the same

speed

121

the relationship of the average kinetic energy of the gas particles to the speed (u) of the particles is:

KE= 1/2mu^2
note: KE and u have lines over them, indicating that they are averages

122

the square root of u^2 (u with a line over it) is called the ..., labeled ..., and is used to indicate the ...

root-mean-square (rms) speed; urms; average speed of a gas

123

from the mathematical treatment of the kinetic theory of gases, we can determine the

relative number of gas particles that have any particular speed

124

root mean square speed is not the same as the

most probable speed (maximum of graph)

125

plots that show speed and number of particles:

maxwell-boltzmann distribution curves

126

if the temperature increases, the ... increases, the curve ..., and both the most probable speed and urms shift to ...

average speed; broadens; greater values

127

the average kinetic energy of the gas particles is proportional to the .., and kinetic molecular theory predicts that the rms speed is related to ... and ... by the equation:

temperature; temperature; molar mass;
urms=√(3RT)/M

128

R in the urms calculation is

8.314 J/molK

129

molar mass in urms is expressed n

kilograms per mole

130

the rms speed of a gas sample is proportional to the square root of ... and inverely proportion al to the square root of ...

temperature; molar mass

131

at constant temp, gases with greater maolar masses ave lower

rms speeds

132

the observation that heavier particles have lower rms speeds is expected because the molecules in a heavier sample must move more ... as thea verage kinetic energies of all gases are the .. at a given temperature

slowly; same

133

diffusion is the

mixing of particles caused by motion

134

the faster the molecular motion, the faster a gas

diffuses

135

the rate of diffusion is always less than the ..., because collisions prevent the particles from ..

rms speed of the gas; moving in a straight line

136

effusion is the passage of a gas through

a small hole into an evacuated space

137

graham's law states that the rte of ... of a gas is ... to the square root of its ...

effusion; inversely proportional; molar mass

138

the kinetic molecular theory explains graham's law because the rms speed of the gas particles is inversely proportional to the

square root of their molar mass

139

rate of effusion of gas a/ rate of effusion of gas B =

√(molar mass of B/ molar mass of A)

140

gases with greater rates of effusion escape through the hole in

shorter lengths of time

141

the time it takes for a gas to effuse, t, is .. to the rate of effusion

inversely proportional

142

most gases obey the ideal gas law quite closely at a pressure o about ... and a temperature well above the ... of the substance

1 atm; boiling point

143

for a gas that follows the ideal gas law, the measured values of PV/nRT graph to a

straight line equalling 1

144

as the pressure increases to high values, ... occur

deviations

145

deviations from the ideal gas law occur under extreme conditions because two of the assumptions of the kinetic molecular theory simply are nto correct when

gas particles are close together

146

these assumptions are: that gas particles are ...; that no ... exist between gas particles

small compared with the distances separating them; attractive forces

147

at high pressure, the volume occupied by the individual individual particles is no longer negligible coompared with the

volume of the gas sample

148

when the particle's size is no longer negligibl, the actual volume available for the gas particles to move is

reduced

149

gas particles that are attracted to each other do not ... as ... as predicted, reducing he ... below that predicted by the ideal gas law

strike the wall; hard; pressure

150

as the pressure increases, he particles are forced ..., making this attractive interaction more important because because more gas particles are ...

closer together; close to the one about to hit the wall

151

at very high pressures, the effect of molecular volume is greater than that of

the attractive forces

152

a gas deviates from the ideal gas law at ... and ... near the ... and at very high ...

temperatures; pressures; condensation point; high pressures

153

the ideal gas law can be modified to include the effects of

attractive forces and the volume occupied by the particles

154

van der waals equation: nRT-

(P + an^2/V^2)(V-nb)

155

n: number of

moles

156

b: constant that depends on the

size of the gas particles

157

a: constant related to the strength of the

attractive forces