Upload
adel-khamis
View
212
Download
0
Embed Size (px)
Citation preview
8/14/2019 wu3c7 by Adel Khamis
1/7
Unit three -77- Chapter Seven
The kinetic theory of gases
and some of its applications
Kinetic theory of gases:
1. A gas is composed of perfectly elastic spheres called ..
2. The intermolecular distances are that the volume of the gass
molecules is negligible compared with the volume occupied by the gas
itself.
3. The intermolecular forces are . due to ., so they are
negligible.
4. Gas molecules are in continuous random motion called . and
during its motion it is colliding and ..
5. The collisions between the molecules are considered as perfectly elastic
collisions, so the kinetic energy of the gas molecules . before
and after the collision, and the velocity before collision .. the
velocity after collision.
6. Gas in thermal equilibrium with .. of container.
The mole:
Definition:
..
..
One mole of any substance contain the same number of molecules, and that
number is known as .
Work Sheet 2008/2009
8/14/2019 wu3c7 by Adel Khamis
2/7
Unit three -78- Chapter Seven
Avogadros law:
Statement:
....
According to Avogadros number and Avogadros law, we can conclude that
one mole of any gas occupy the (same / different) volume.
The mole of any gas occupy . liters at S.P.T
Calculate the number of molecules, and the volume occupied by 0.1 kg of
oxygen [o16] given that NA = 6.023x1023
....
Density:
1. Definition:
2. Rule:
3. For certain amount of gas contain N molecules and the mass of each
molecule is m, the total mass of the gas equal:.
4. The density of the gas (in terms of mass of molecule) =
Example:
Given that the density of hydrogen gas is 0.09 kg/m3 find the mass of
hydrogen molecule, if 1020 molecules occupy 100 cm3.
Work Sheet 2008/2009
.........
............
=
8/14/2019 wu3c7 by Adel Khamis
3/7
Unit three -79- Chapter Seven
..
[9x10-26kg]
Pressure:
1. Pressure (definition):
2. Pressure (rule):
3. Momentum equal (rule): .
4. Force (Definition):
5. Force (rule): .
Considering cubic vessel of lenght (l) contains certain number of molecules
of gas:
6. Linear Momentum of one molecule before impact = .
7. Linear Momentum of one molecule after impact = .
8. The change in linear momentum = .
9. The change in momentum delivered to the wall =
.
10. Force of one molecule = =
11. From the law of velocity, t = = .
12. From (10 & 11) Force = ...
13. For the total number of molecules (N), F = ..
14. From (2 & 13) P = .
Work Sheet 2008/2009
8/14/2019 wu3c7 by Adel Khamis
4/7
Unit three -80- Chapter Seven
15. The area of the cube base = , and the volume of cube
.
16. From (14 & 15) P = .
17. Generally, in the three dimension: V2 = . + .. +
., and since Vx2 = Vy
2 = Vz2, therefore V2 = ..
18. Therefore: Vx2 = .
19. From (16 & 18) P =
20. Density = .
21. From (19 & 20) P =
22. Velocity =
Where: v is called ..
23. Impulse = = =
N.B.:
Number of collision per unit time can be calculated from the relation
.
Work Sheet 2008/2009
8/14/2019 wu3c7 by Adel Khamis
5/7
Unit three -81- Chapter Seven
The Scientific Concept of Temperature:
The number of molecules in one mole of any gas is constant and called
.. (NA = 6.023x1023 molecules)
Macroscopic theory Microscopic theory
For any amount of gas
PVol = . PVol = .
For one mole of gas
N = .
n = .
PV = . PV = .. = ....
NAmv2 =
..............
..............2=mv
mv2 = .
(where K called ..)
Kinetic energy Temperature
mv2 = ..............
..............2=v
K.E = ..
..........
..........=v
K.E depends on Velocity depends on ..
and .
Where:
R is called (R = 8.31, and its
unit is )
K is called ............
........=K (K = 1.38 x 10-
23 J/K)
Work Sheet 2008/2009
8/14/2019 wu3c7 by Adel Khamis
6/7
Unit three -82- Chapter Seven
N.B.:
The number of molecules in one mole of any gas is constant and called
. (NA = 6.023x10
23
molecules)
One mole of any gas occupies .. liter at SPT
It is (possible / impossible) for two gases to occupy the same volume at
the same time. (Give reason)
The total pressure of two gases at the same container =
.
Give reasons:
R.M.S.S does not affect by pressure.
There is no Hydrogen gas in the earths atmosphere.
Examples:
1. If the density of the hydrogen at normal temperature and pressure (NTP)
is 0.089 kg/m3, calculate the root mean square speed of its molecules.
.
.
.
.
[1847.87 m/s]
Work Sheet 2008/2009
8/14/2019 wu3c7 by Adel Khamis
7/7
Unit three -83- Chapter Seven
2. Calculate the number of molecules per unit volume of oxygen at NTP
using the following data:
v = 4.62 x 102 m/s
m = 52.8 x 10-27 kg.
.
.
.
.
[2.7x1025]
3. Nitrogen gas in a container at NTP. Calculate the root mean square speed
of its molecules given that the mass of one Nitrogen mole is 0.028 Kg
and occupies 22.4 liters at NTP and that Avogadros number equals 6.02
x 1023 Molecules, Boltzmanns constant equals 1.38 x 10-23 J/K.
[493 m/s]
Work Sheet 2008/2009