1) The document discusses several gas laws including Boyle's law, Charles' law, Dalton's law of partial pressures, and Avogadro's hypothesis. It explains concepts such as critical temperature and how gas laws can be applied to anesthetic practices. 2) Specific applications covered include using Boyle's law to calculate oxygen cylinder contents, the principle of the hydrogen thermometer, clinical uses of Dalton's law, and calibrating a vaporizer using Avogadro's hypothesis. 3) The document also discusses adiabatic changes in gases, how the cryoprobe works, filling oxygen and nitrous oxide cylinders, and defines critical temperature as the temperature above which a substance cannot be liquefied no matter

1. MOHAMED ANWER RIFKY
4-THE GAS LAWS
A-THE USE OF BOYLE'S LAW TO CALCULATE THE
CONTENT OF AN OXYGEN CYLINDER.
B-THE PRINCIPLE OF THE HYDROGEN
THERMOMETER.
C-WHAT ARE THE CLINICAL APPLICATIONS OF
DALTON'S LAW.
D-STATE THE AVOGADRO'S HYPOTHESIS,
MEANWHILE,SHOW HOW TO CALIBRATE OF A
VAPORIZER BY USING THIS HYPOTHESIS ?.
E-THE FORMULA OF THE UNIVERSAL GAS
CONSTANT APPLIED IN ANAESTHETIC PRACTICE.
F-WHAT IS THE TEMPERATURE ABOVE WHICH A
SUBSTANCE CANNOT BE LIQUEFIED HOWEVER
MUCH PRESSURE IS APPLIED?,IN ADDITION
SHOWING THE FILLING OF OXYGEN AND NITROUS
OXIDE CYLINDERS.
G-EXPLAIN IN DETAILS THE TERM OF PSEUDO
CRITICAL TEMPERATURE.
1-Consider the hypothetical case of a nitrous oxide cylinder filled completely
with liquid nitrous oxide.
2-(liquid is not compressible)>>much increase in pressure with temp. increase,with risk of
explotion.
Filling ratio:
Mass of gas in a cylinder divided by the N.B (TO BE IN CLUDED IN THE LAST
SLIDE). mass of water (1 litre water = 1 kg).For nitrous oxide it's
0.65 in the United Kingdom.

2. A-MOLECULAR THEORY:
**In a solid, the atoms or molecules are usually arranged in a
regular formation called a lattice-In a liquid the molecules exert >> forces of attraction
(Van der Waals' forces) -If heat is added to a liquid>>overcome the Van der Waals'
>> gas.
**At any temperature an equilibrium occurs between the two rates of
molecular
transfer, and the vapour above the liquid is said to be
saturated>>(SVP).
**If the liquid is heated to its boiling point, the energy
is so great ( more collision)>>>gaseous phase.(pressure = atm pr. ).
B-THE GAS LAWS:
PV = Constant (K1) >>> First law.
Boyle*s law states that at constant temperature the
volume of a
given mass of gas varies inversely with the absolute
pressure.
The second perfect gas law, known also as Charles's law
or Gay
Lussac's law.
Charles's law states that at constant
pressure the volume of a
given mass of gas varies directly with the
absolute temperature.
Gases expand when they are heated.( less dense ).Convection
current.
The third of the gas
laws
The third perfect gas law states that at constant volume the
absolute
pressure of a given mass of gas varies directly with the
absolute temperature.
The hydrogen thermometer,as a clinical
applicatiomn.
C-ADIABATIC CHANGES OF STATE IN A GAS: The behaviour of a gas changes if heat is added or taken from it.but it can also be
altered without
allowing the gas to exchange heat energy with its surroundings.
1-Compressed in an air supply unit>>the temperature of the
air rises
>>a system of cooling is needed.Or,cylinder is
turned on quickly, the pressure of gas in the
connecting system rises rapidly>>, the gas is compressed
adiabatically and a large temperature rise (risk of fire).
2-If a compressed gas expands
adiabatically,
cooling occurs as in the cryoprobe.
D-THE CRYOPROBE:
The cooling of a cryoprobe >>an adiabatic process-Gas is
allowed to expand rapidly out of a capillary tube.When applied to
nerves it causes local degeneration >>(3-6 months)..overcome
the Van der Waals' forces of attraction>>.Temperature as low as
—70°C.
E-DALTON'S LAW OF PARTIAL PRESSURES: Dalton's law of partial pressures states that in a mixture of gases
the pressure exerted by each gas is the same as that which it
would exert if it alone occupied the container.
1-The pressure exerted by the nitrous
oxide in the cylinder = if it alone occupied
the
container.
2-The available space oxide is increased ( half >full
cylinder).
3-(Boyle's law) pressure in the cylinder>> halved from 100 kPa to 50
kPa.
4-A cylinder of air at
(100 kPa.). The 20.93% oxygen >>
pressure of 20.93 kPa and the nitrogen pressure is 79.07 kPa.
Entonox
AIR CYLINDER
5-The oxygen partial pressure (157 mmHg), and
nitrogen
6-Filling of a cylinder to produce a
10%
carbon dioxide in oxygen mixture.
CO2+O2 FILLING.

3. F-AVOGADRO'S HYPOTHESIS: 1-Avogadro's hypothesis states that equal volumes of
gases at the
same temperature and pressure contain equal numbers of
molecules.
2-The molecular weights and masses of of oxygen and hydrogen are
different>>number of molecules>>quantity of subs.
3-A mole >>same number of
particles as there are atoms in 0.012 kg of carbon
12.
4-One mole of any other substance contains 6.022
X
(10 to ! power of 23 particles) (Avogadro's
number).
5-One mole of any gas at standard temperature and pressure
occupies 22.4 litre, and that (2gm of H2 or 32 gm of
O2>>!!).C02=44 !!
6-As an example of the mole and Avogadro's
hypothesis>>
(calibration of a vaporizer). 14.45 gm isoflurane( 1/10
mole) into a volume of 224 litre>>1%. (temperatures and
pressures other than s.t.p.,!!!).
7-44 g (1 mol) nitrous oxide occupies 22.4 litres at
s.t.p.
N.B (1800 litres at
15°C).
**Weight of nitrous oxide is used to indicate how full the
cylinders are (tare weight).
G-UNIVERSAL GAS CONSTANT:
Avogadro’s hypothesis and the
mole >>
>>> {PV = nRT ,where n (no. moles)}.
>>Gauge of a gas cylinder.
Volume in the
equation is constant., R is a
constant and if temp.is constant>>
Pressure gauge thus acts as a
content gauge.
H-CRITICAL TEMPERATURE:
1-Hydrogen obeys the gas laws most closely (Hydrogen
thermometer). 2-Nitrous oxide liquefies without
further increase of pressure until the cylinder is filled to the appropriate LEVEL.
3-It is impossible to turn the
oxygen into its liquid form at normal room
temperature.
(Below—119°C, then it would be possible to liquefy the
oxygen).
Critical temperature is defined as the temperature above
which a
substance cannot be liquefied however much pressure is
applied.
(The critical temperature of nitrous oxide is
36.5°C).
4-Pressure against volume at various temperatures
(isotherms)>>
series of lines >> >
(At 40°C, 36.5°C, and 20 C).
1-Smooth increase in
pressure according to Boyle's
law.
(Rectangular
hyperbola).
2-At the critical temperature (36.5°C) >>critical pressure
of 73 bar at which the nitrous oxide liquefies,and slightest
decrease in vol.>greater increase in pr.
3-Of greater interest is the bottom isotherm,
illustrating the results at a room temperature of 20°c.
**Both liquid and vapour are present and any further
decrease in volume>>more vapour to condense and the
pressure >>unaltered.
**A horizontal line is present on the graph at 52 bar>
typical pressure in a nitrous oxide cylinder at room
temperature.
The word nitrous oxide gas is used for the upper tracing
and nitrous oxide vapour for the lower tracing
Critical temperature applies to a single gas.Entonox' mixture of 50% nitrous oxide and 50% oxygen>>specific critical
temperature at which the gas mixture may separate>>below -5.5°C (cylinder),and below — 30°C at pipeline pressure of 4.1
bar (Pseudo Critical .Temp.).