Poisons are substances that cause illness and death when absorbed by the body. Antidotes counteract or oppose the effects of poisons and are used to treat poisoning. There are three types of antidotes - physiological antidotes counteract poison effects chemically, mechanical antidotes prevent poison absorption, and chemical antidotes convert poisons to non-toxic compounds. Sodium thiosulfate and sodium nitrite are antidotes used to treat cyanide poisoning.

2. POISON :
Any substances that when enter in to or
absorbed by the body cause illness and death
is called poison.
ANTIDOTE :
The substance that counteract or oppose the
action of poison or used in the treatment of
poison are called antidote.

3.  PHYSIOLOGICAL ANTIDOTE :
These are the substance that counteracts the
effect of poison
ex : sodium nitrite
 MECHANICAL ANTIDOTE :
These are the substances that prevent
absorption of toxic substance in to the body
ex : activated charcoal
 CHEMICAL ANTIDOTE :
These are the substance that convert poison to
non toxic compound by altering chemical nature
of poison

4.  Sodium thiosulfate is an inorganic compound
with the formula Na₂S₂O₃xH₂O. Typically it is
available as the white or colorless pentahydrate,
Na₂S₂O₃·5H₂O. The solid is an efflorescent
crystalline substance that dissolves well in
water.
 Formula : Na2S2O3 . 5H2O
 IUPAC ID : Sodium thiosulfate
 Molar mass : 248.17
 Density : 1.67 g/cm³
 Melting point : 48.3 °C
 Soluble in : Water

5. PREPARATION
 It is made by treating sodium sulphite
solution with sulphur in the absence of air
Na2SO3 + S = Na2S2O3
 It can also be prepared by sulphur dioxide
sodium sulphide.
2Na2S + 3SO2 = Na2S2O3 + S

6. PROPERTIES
 It occurs as colorless monoclinic crystals or
crystalline powder.
 It is odourless and has a saline taste.
 It is very soluble in water and insoluble in
alcohol.
 At 200°C , It get decomposedcompletely in to
sulphur , sulphur dioxide, sodium sulphide and
sodium sulphate.
IP LIMIT
 Contains not less than 99.0% and not more than
101.0%

7. ASSAY
REDOX TITRATION ( IODOMETRY METHOD )
Dissolve an accurately weighted amount of
substance in water , add starch mucilage as
indictor and titrate with 0.05M iodine untill
the appearance of blue colour.
Na2S2O3 + I2 = Na2S4O6 + 2NaI
Each ml of 0.05M iodine is
equivalent to 0.02482 gm
of Na2S2O3 . 5H2O

8. USES
 Sodium thiosulfate, also spelled sodium
thiosulphate, is used as a medication to treat
cyanide poisoning, pityriasis versicolor, and to
decrease side effects from cisplatin. For cyanide
poisoning it is often used after
the medication sodium nitrite and typically only
recommended for severe cases.

9.  Sodium nitrate is the chemical compound with
the formula NaNO2. This alkali metal nitrate salt
is also known as Chile saltpeter to distinguish it
from ordinary saltpeter, potassium nitrate. The
mineral form is also known as nitratine, nitratite
or soda niter.
 Formula : NaNO2
 IUPAC ID : Sodium nitrate
 Molar mass : 69
 Melting point : 308 °C
 Boiling point : 380 °C
 Density : 2.26 g/cm³

10. PREPARATION
 It is prepared by reducing sodium nitrate
with lead or sulphur / sodium hydroxide
NaNO3 + Pb = NaNO2 + PbO
3NaNO3 + S + 2NaOH = 3NaNO3 + Na2SO4 + H2O
 It can also be prepared by treating oxides of
nitrogen with sodium carbonate
Na2CO3 + NO2 + NO = 2NaNO2 + CO2

11. IP LIMIT
Contains not less than 97.0% and not more than
101.0%
ASSAY
Disssolve an accurately weighted amount of
substances in water and transfer in to a
combination of KMnO4 , water and sulphuric
acid. Add know excess of oxalic acid and heat
the reaction mixture to 80°C and titrate with
0.1M potassium permanganate solution.
NaNO2 + H2SO4 = HNO3 + NaHSO4
HNO2 + O = HNO3

12. USES
Used as a food preservative and antidote to
cyanide poisoning. It has a role as an
antimicrobial food preservative, an
antihypertensive agent, a food antioxidant, a
poison and an antidote to cyanide poisoning. It is
a nitrite salt and an inorganic sodium salt.

13.  SYMBOL : C

14.  It is prepared by igniting carbonaceous matter
such as coal or wood in the presences of limited
amount of air and allowing it to burn for some
time. Then the air is cut off and then it is
activated by heating at high temperature in a
stream of gas either carbon dioxide or steam
with or without the addition of some inorganic
salts

15.  It is black powder free from gritty particles.
 It is odourless
 Insoluble in all the usual solvents.
STANDARD
The adsorbing power should not be less than 40%
of its own weight of phenazone.
ASSAY
( DETERMINATION OF ADSORPTION POWER )
Weight accurately about 0.3 g of sample and mix
well 25 ml of phenazone solution ( 0.25 g in 25ml
water ). Shake well for 15min and filter. Discard

16. The first 5ml of filtrate. To the next 10ml of
filtrate add 0.1 gm potassium bromide and 20ml
dil HCl . Then add 0.1 ml of ethoxychysoidine
solution as indicator and titrate slowly ( one
drop per 15 sec ) with 0.1M potassium bromated
solution until the colour changes from reddish
pink to yellowish pink. Perform the blank
titration using 10ml of phenazone solution.

17. USES
 Purpose of review For decades, activated
charcoal has been used as a 'universal antidote'
for the majority of poisons because of its ability
to prevent the absorption of most toxic agents
from the gastrointestinal tract and enhance the
elimination of some agents already absorbed.