Chapter 6 Gas Flashcards

1
Q

Properties of Gas

A
A. Gases have an indefinite shape.
B. Gases have a low density
C. Gases are very compressible
D. Gases exert pressure equally in all
directions on the walls of a container.
E. Gases mix spontaneously and completely
with one or more other gases.
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2
Q

a gas consists of?

A

small particles that move rapidly in straight lines

- indefinite shape; mix spontaneously

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3
Q

compared to the volume of the container they occupy gas particles have?

A

very small volumes

- low density; compressibility

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4
Q

gas particles having essentially no attraction or repulsion towards one another means..

A

they colide frequently with each other and with the walls of the container, the ollisioins are perfectly “elastic”

  • no loss of energy
  • exert pressure in all direction
  • kinetic energy of gas particles affects the pressure/volume
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5
Q

the average kinetic energy (energy of motion) of the gas particles are?

A

directly proportional ot its absolute temperature

kelvin temperature

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6
Q

what are the 4 variables of the physical behaviors of gases

A

pressure P
volume V
temperature T
amount n

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7
Q

pressure

A

the force exerted by gas against the walls of the container

- atm; mm Hg: torr; pascal

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8
Q

volume V

A

the space occupied by the gas

- L; mL

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9
Q

temperature T

A

determines the kinetic enegy and rate of motion of the gas particles
- C; K

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10
Q

amount n

A

the quantity of gas present in a container

- g; moles

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11
Q

Pressure of A Gas

A

gas pressure is the force acting on a unit area
Pressure P = (Force/area)

  • pressure is indicated by Δh (mm) of Hg column
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12
Q

atmospheric pressure

A
  • pressure exerted by a column of air from the top of the atmosphere to the surface of the earth
  • about 1 atm at sea level
  • lower at high altitudes where the density of air is less
  • is affected by weather, being lower on a rainy day than on a sunny day
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13
Q

atmospheric pressure at sea level is about 1 atm = (mmHg, torr, psi, kPa)

A
1 atm = 760 mmHg (exact)
1 atm = 760 torr
1 atm = 14.7 psi (lb/in.2
)
1 atm = 101.325 kPa (kiloPascals).
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14
Q

temperature
- the property of a gas is related to the kinetic energy (speed) of the gas particle, thus the absolute temperature kelvin

A

K = oC + 273.0

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15
Q

the volume of a gas is the

A

volume of the container it occupies

- L or mL

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16
Q

the property of a gas is related to?

A

the number of as particles in the same, NOT the nature of gas particles
- moles (av.#)

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17
Q

the 4 variable of a gas PVTn are interdependent

A

Any one variable can be determined by
measuring the other three.
In the laboratory, scientists often hold 2
variables constant and then observe how the
other 2 variables change with respect to each
other

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18
Q

Boyle’s law (for pressure and volume)

A
• At constant temperature, the
pressure of a fixed amount of gas
increases, when the volume
decreases.
• At constant T and n, V of a gas is
inversely related to its P.
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19
Q

Boyle’s law formula

A

P1V1 = P2V2

Kinetic Molecular Theory: when the volume decreases, the
gas particles moves in smaller space, thus colliding more
often with the wall and exerting higher pressure.

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20
Q

Charle’s Law for temperature and volume

A
At constant pressure
,
The volume of a fixed
amount of gas is directly
related to its Kelvin
temperature.
21
Q

Charles law formule

A

V1 = V2
__ ___
T1 T2

22
Q

Kinetic molecular theory of charles law

A

: As Tk increases, gas particles move
faster and collide more with the wall, thereby expanding the
volume of container until the inside pressure equals the
outside pressure.

23
Q

Avogradro’s law

for volume and moles of the gas

A
At constant P and T,
the volume (v) of a gas is
directly related to the
number of moles
(
n) of gas
24
Q

avogrado’s law formula

A

V1 V2
__ = ___
n1 n2

25
kinetic molecular theory of avogradro's law
When the number of gas particles increases, so does the number of collision on the wall, thereby expanding the volume until the inside pressure equals the outside pressure
26
The ideal gas law formula
PV = nRT universal gas constant R = 0.0821 (atm-L/mol-K)
27
Combined gas law
P1V1 P2V2 ____ = _____ T1 T2 (nature of the gas does not matter)
28
partial pressure | - the pressure of a gas in a mixture
at a given T, in a given container, the pressure of a gas is the same with or without the presence of other kinds of gas particle. The partial pressure of a gas (in a mixture) is the same as the pressure of the gas if it were alone in the container
29
Dalton’s Law of Partial Pressures
The total pressure exerted by gases in a mixture is the | sum of the partial pressures of those gases.
30
physical states of matters | Gas
indefinite shape indefinite volume compressibility low density g/L
31
physical states of matter | liquid
indefinite shape definite shape not compressible g/ml density
32
physical states of matter solid
definite shape definite volume not compressible density g/cm3
33
Solid kinetic-molecular view
fixed, very close arrangement of particles very strong interaction between particles very slow movement of particles
34
liquid kinetic-molecular view
- random, close arrangement of particles - strong interaction between particles - moderate movement of particles
35
gas kinetic-molecular view
- random, far apart arrangement of particles - essentially none interaction between particles - very fast movement of particles
36
inter-particle attraction in Liquid and Solid | - ionic compound
solid at Tr - smallest particles = ions - electrostatic attraction among cations and anions = ionic bonds (chemical bonds)
37
Inter particle attraction in Liquid and solid | - covalent (molecular compounds)
``` smallest particle = molecules attraction within molecule= covalent bond (chemical bond) attraction between molecules = intermolecular force (IMF) ```
38
3 types of intermolecular force (IMF)
``` polar covalent compounds - dipole-dipole attraction - hydrogen bonds Nonpolar covalent compounds - dispersion force ```
39
dipole - dipole attraction
attractive forces between the positive and negative “poles” of different polar molecules.
40
hydrogen bonds
A very strong Dipole-Dipole Force found between or in molecules that contain H-F, H-O, H-N bonds
41
dispersion forces
weak attraction caused by temporary dipoles that develop when electrons are not distributed equally
42
criteria's for hydrogen bonds
``` Hydrogen atoms that are covalently bonded to F, O, and N atoms only may participate in hydrogen bonding. • Similarly, the lone pairs on a F, O, or N atom of another molecule may participate in hydrogen bonding. • There are no exceptions to this ```
43
London dispersion force
- transient, weak attraction among non-polar molecules -LDF is transient and weak. Only at very 4.2 K (-268.8◦C), when He atoms move very slowly, attraction by LDF is strong enough to hold He atoms in the liquid state. The boiling point (condensation point) of He gas is 4.2 K!
44
Gas - imf
- No IMF Gas to solid = deposition gas to liquid = condensation
45
solid - imf
-High IMF Solid to liquid = melting solid to gas = sublimation
46
liquid - imf
- lower imf liquid to gas = vaporization liquid to solid = freezing`
47
IMF heat absorbed
Sublimiation melting vaporization
48
IMF heat released
deposition freezing condensation