Medicinal gases, Pharmaceutical inorganic chemistry, first year B.pharmacy

1. MEDICINAL GASES
NASTARAN KHOJASTEHPOUR
JKKN COLLEGE OF PHARMACY
Dr.MGR MEDICAL UNIVERSITY- CHENNAI

2. Medicinal gases:
Gases; produced, packed and used for diagnosis,
therapy, anaesthesia.
Oxygen (O2)
Carbon dioxide (CO2)
Nitrous oxide (N2O)
Nitrogen (N2)
Helium (He)

3. Oxygen (O2)
Essential for animal and human
21% of atmosphere
Preparation:
1) fractional distillation of liquid air
2) electrolysis of water

4. Properties:
colourless, tasteless, odourless gas
Slightly heavier than the air
liquified at – 118.8o C
Sparingly soluble in water
Freely soluble in alcohol

5. dissociation at 5000o c to atomic form
which is much more active
Combines with most metals
Cause corrosion
S + O2 -----> SO2
C + O2 -----> CO2
2Mg + O2 -----> 2MgO

6. Identification test:
1) cause glowing splinter to burn brightly
2) oxygen is absorbed when shaken with alkaline
solution. The solution turn to dark brown.
3) oxygen mix with equal volume of nitric oxide
and produce red fumes.

7. Standard: not less then 99%
Storage:
should be stored under compression in
appropriate metal cylinder with prescribed
safety regulations.
Valves should not be lubricated with oil.
Shoulder of cylinder = white , cylinder = black
Name of the gas on the label on shoulder and
painted on the cylinder.

8. Use:
Medical gas
Essential for breathing
Administered in respiratory difficulties
(asthma), during surgery
Used with He and CO2.
Liquid oxygen used for removing warts

9. Assay:
A certain volume of the gas is drawn
into the gas burette and allowed to mix
with the absorption liquid. The volume
of the residual gas is measured.

10. Carbon dioxide (CO2)
Storage:
should be stored liquified under pressure in
appropriate metal cylinder.
Metal cylinder = grey.
Name of the gas on the label on shoulder
and painted on the cylinder.

11. Use:
Medical gas.
CO2 (5%) with O2 stimulate respiration in
poisoning by CO and morphine.
Used for manufacture of chemicals (sodium
bicarbonate, sodium carbonate, soda water.
Acts as carminative and promote absorption in
the stomach.

12. Nitrous oxide (N2O)
Properties:
colourless, tasteless, odourless gas.
One and a half heavier than the air.
soluble in water.
Freely soluble in alcohol.
It can be liquified.

13. Boils at -89o c.
decompose into nitrogen and oxygen
by heating.
2N2O -----> 2N2 + O2
Laughing gas: produce exhilarating
effects when inhaled

14. Storage:
should be stored under compression in
appropriate metal cylinder with prescribed
safety regulations. At a temperature not
exceeding 37o C.
Valves should not be lubricated with oil.
Color of cylinder = blue
Name of the gas on the label on shoulder and
painted on the cylinder.

15. Use:
Medical gas.
General anaesthetic and analgesic for
minor operation (tooth).
Removal of abscesses.
Calming excited mental patients.
Antioxidant.

16. Assay:
In this assay a special apparatus is
used. Nitrous oxide is condensed by
using liquid nitrogen, the non-
condensable volume of the gas is
measured.

17. Nitrogen (N2)
Storage:
stored under pressure in a gas cylinder.
Use:
vitamin and fish oil preparation.
Postpone or prevent oxidation.
Manufacture of ammonia, nitric acid,… .
filling electric lamps.
liquid nitrogen used for freeze water.

18. Helium (He)
Inert gas, always present in the free state.
Preparation:
1) by fractional of the liquid air, liquid He
boils at 4o K.
2) from natural petroleum gas by
liquification at low temperature.

19. 3) by heating monazite to 1273o K or by
heating with dilute sulphuric acid.
4) dry air is passed over heated copper foe
removing oxygen and the air is passed over
heated Magnesium to remove nitrogen.
(for several times). The residual air is only
a mixture of the noble gases.

20. Properties:
colourless, tasteless, odourless gas.
After hydrogen it is the lightest substance
known.
Soluble in water
Monoatomic
can be liquified under pressure.
Absorbed by coconut charcoal at low
temperature.
Liquid He exhibits unusual properties.

21. If He is cooled below 2.18o K, a new form of He,
called hell is obtained.
It behaves like a solid but with properties of a gas.
Viscosity is very low.
Thermal conductivity is very high.
It is able to rise against gravity.

22. Storage:
should be kept at pressure of 132
atmosphere.
Metallic cylinder in cool dry place.
The body and the valve end of gas
cylinder = brown
Cylinder containing He and O2 mixture,
body painted black, valve end paint white
and brown.

23. Use:
Medical gas.
A mixture of He (79%) and oxygen (21%) is
administered for respiratory distress
(asthma).
Because of lightness and non-inflamability
used for inflating tyres of airplanes and
filling the balloons.

24. Assay:
Impurities in He (nitrogen) can be
absorbed by coconut charcoal cooled by
liquid oxygen. A sample of the gas is
introduced in to a gas bulb containing
coconut charcoal cooled by liquid
oxygen. The unabsorbed gas (He) is
pumped out and measured.

25. WITH THE BEST WISHES