Gases Flashcards
What is the major difference between the states of matter?
The arrangement of particles
Solid have
Definite volume
Definite Shape
Liquid have
Definite volume
Indefinite shape
Gas have
Indefinite volume
Indefinite shape
What is the physical significance of having the gas’ arrangement of particles?
It is compressible
The volume of a gas changes significantly with:
Pressure, temperature, gases flow freely, gases generally
Characteristics of gases
Gases flow freely, gases generally mix in all proportions
Major Characteristics of gases
Expansibility
Compressibility
Pressure
Effect on heat
Diffusibility
The collision of gases particles on the walls of the container gives rise to
Pressure
SI unit of pressure
Pascal
Formula for pressure
Force/ area
This may either be in terms of grams or moles
Amount
SI unit of amount
Moles
Formula for amount of substance
Grams/ molar mass
The amount of space that is to be occupied by gaseous state
Volume
SI unite of volume
Cubic meter
Relates to the average kinetic energy of gaseous particles
Temperature
SI unit of temperature
Kelvin
Celsius to Fahrenheit
(9/5 x C) + 32
Fahrenheit to Celsius
(5/9 x F) - 32
A parameter that describes gases, which have an SI unit of Joule
Energy
equivalent of 1 cal to joule?
4.184 J
What is the values for Universal Gas Constant in correct units?
8.314 J/ mol K
0.08205 L atm/ mol K
1.986 cal/ mol K
Pressure in STP
1 atm/ 101.3 kPa
Temperature in STP
0 C/ 273.15 K
Molar volume in STP
22.4 L/ atm
No. of moles in STP
1 mol
Enumerate the 5 kinetic molecular theory of gases
- Gases travel in straight lines and random directions
- Small particle sizes to be negligible
- Atomic collision are perfectly elastic, KE is conserved
4.Gas particles do not repel or attract - KE of gas is directly proportional to Kelvin Temperature
What are the parameters that describes gases
Pressure, temperature, amount, volume
Describe charles law and formula
States that there is a direct relationship between the gas volume and temperature
V1/T1 = V2/T2
Describe boyles law and formula
States that there is an indirect relationship between the gas volume and pressure
V1P1 = V2P2
Describe Gay-lussac law and formula
States that there is a direct relationship between the gas pressure and temperature
P1/T1 = P2/T2
Describe avogadros law and formula
States that there is a direct relationship between the gas volume and number of moles
V1/N1 = V2/n2
The total pressure of a mixture of gases is equal to the sum of the pressures of all the gases present.
Daltons Law of Partial Pressure
Give formula of Partial Pressure
P total = (n1 + n2 + n3 …) (RT/V)
Phenomena which results in the net
movement of particles from a region
of high concentration to a region of
low concentration in response to a
concentration gradient
Graham’s law of diffusion
Under same conditions of constant temperature and pressure, the rates of diffusion of different gases are ____________ to the square roots of
their molecular masses.
inversely proportional
Formula for Grahams law of diffusion
rate2/rate1 = Square root M1/M2
net movement of particles through
an opening smaller than the mean
free path of the gas (no collisions)
Effusion
net movement of particles from a
region of high to low concentration
as influenced by collisions
Diffusion
Formula for Graham law of effusion
Effusionrate2/ Effusionrate1 = Square root M1/M2
Formula for average KE of a gas molecule
e = 3RT/ 2N0
In deriving the kinetic gas equation, what
was the assumption made regarding the
velocities of the gaseous molecules?
Constant velocity for all molecules.
The velocity place in the utmost peak in of molecular velocity graph
Most probable velocity
Located after the most probable velocity
average velocity
The farthest velocity from the most probable velocity
Root mean square velocity
Distance travelled by a molecule between two successive collisions
THE MEAN FREE PATH
Relationship of mean free path to
pressure;
volume; and
temperature
Indirectly Proportional
Indirectly Proportional
Directly Proportional
If collision diameter is large, mean free path will _____
Smaller
Relationship of collision diameter to the mean free path
If collision
diameter is large, mean free path will be smaller!
amount of heat required to raise the temperature of one gram of a substance by 1°C
may be measured at constant volume or constant pressure
Specific Heat Ratio of Gases
The Vibrational and rotational degrees of freedom in monoatomic gases
Zero
volume kept constant while allowing pressure to increase
Specific Heat at Constant Volume
pressure kept constant while allowing volume to increase
Specific Heat at Constant Pressure
Two applications of heat in Specific Heat at Constant Pressure
- Increase KE of molecules
- Performing expansion work
What specific conditions do ideal gases work in?
High temperature
Low pressure
The deviation of the compression factor from unity is a measure of
Nonideality of gas
At very low pressures, Z will be
approximately ____ for all the gases
1
Deviation from ideality becomes
much _____ at high temperatures
lesser
At low pressures and high temperatures, real gases approach _____ and so obey the ideal gas equation
ideality
At low temperatures and sufficiently high pressures, the gas behaves as
Real gas
Larger deviations are primarily observed when the gas is closer to its
liquefaction point
Ideality satisfied at ____
temperatures and ____ pressures
high, low
Because of the existence of attractive forces, pressure is ______ for a real gas
lesser
Since the non-volume postulate is no longer valid, volume is _____ for a real gas
Larger
Related to
the effective /excluded volume
van der Waal’s Constants, b
Related to the strength of the
interactions between your molecules
van der Waal’s Constants, a
When gases are compressed, it
Liquefies
Temperature above which it cannot be liquefied no matter how much pressure is applied
CRITICAL TEMPERATURE, Tc
Minimum pressure required to liquefy the gas at its critical temperature
CRITICAL PRESSURE, Pc
Volume occupied by a mole of the gas at the critical temperature and critical pressure.
CRITICAL VOLUME, Vc
When a gas is at its critical temperature and critical pressure the gaseous and liquid phase lose their discernible boundary
(known as the critical phenomenon) and the gas is in its
critical state
What are the 5 Kinetic Molecular Theory of Gases
- Gases travel in straight lines and in random directions
- Gases particles are so small that their size is negligible
- Atomic or molecular collisions are perfectly elastic and so kinetic energy is conserved
- The gas particles are assumed not to attract or repel each other.
- The average kinetic energy of the gas particles is directly proportional to the Kelvin temperature.
In deriving the kinetic gas equation, what was the assumption made regarding the velocities of the gaseous molecules?
.
Constant velocity for all molecules
