93
Sodium and potassium nitrate(III)
Do not confuse these compounds with sodium nitrate(V) and potassium nitrate(V).
Sodium nitrate(III)
Potassium nitrate(III)
Oxidising
O
Toxic
T
Dangerous for the
environment
N
Store: T
Sodium nitrite
NaNO2
Potassium nitrite
KNO2
R8: Contact with combustible material may cause fire. R25: Toxic if swallowed.
R50: Very toxic to aquatic organisms.
-3
Solutions equal to or stronger than 3.5 mol dm should be labelled TOXIC. Solutions
-3
-3
equal or greater than 0.4 mol dm but less than 3.5 mol dm should be labelled
HARMFUL.
Dangerous with: ACIDS. Nitrogen oxides are given off.
COMBUSTIBLE MATERIALS. Wood, clothes etc impregnated with the solution ignite
easily and burn vigorously when dried.
AMMONIUM SALTS, CYANIDES, THIOSULFATES. Explosive, unstable mixtures are
formed. They may explode even on contact.
PHENOL. An explosive, unstable mixture is formed.
The reactions between nitrites and secondary & tertiary amines should not be
carried out, even as a test, because the products are carcinogenic.
Emergencies: see standard procedures on Hazcard E, BUT ALSO:
If spilt on skin or clothes: Remove contaminated clothing. Wash off the skin with
plenty of water. Soak contaminated clothing and rinse repeatedly.
If spilt in the laboratory: Wear goggles. Scoop up as much solid as possible. If in
solution, add mineral absorbent and treat as a toxic spill. Rinse the area with water
and clear up. It is essential to ensure that no significant impregnation of wood, cloth or
other combustible matter occurs.
Disposal: W1, Wspec
3
Wspec:
For 25 g amounts, dissolve in 500 cm of water in a 1 litre beaker, add 25 g
of ammonium chloride and heat to boiling. Wear goggles. The gas evolved
is nitrogen and the nitrite is completely destroyed.
For emergencies, see Hazcard E as well as more detailed information which may be on this Hazcard.
© CLEAPSS 2007
93
Sodium and potassium nitrate(III)
Activity
Use of
solutions
User
Y9
Control measures
Wear eye protection.
Preparation of
nitrogen
Y9
Wear eye protection.
Diazotisation
of aromatic
amines
Y12
Wear eye protection.
Do not prepare any that
involve the use of old
samples of naphthalenols.
Preparation of
nitric(III) acid
(nitrous acid)
Y12
Preparation of
ammonium
nitrite
-
Wear eye protection.
This must be made just
before it is required.
A fume cupboard may be
required for larger volumes of
material.
Do not attempt to prepare
the solid salt.
Model risk assessments
Experimental points
Use a 0.1 mol dm solution prepared by a teacher or technician.
It decolourises acidified potassium manganate(VII) solution. It
produces iodine from potassium iodide solution with the release
of nitrogen monoxide gas. With iron(II) sulfate(VI) solution, it
produces a brown colouration.
3
-3
3
Mix 2 cm of 1 mol dm ammonium chloride and 2 cm of
-3
1 mol dm sodium nitrite solutions. Do not warm. Older
students can use larger quantities.
Some azo dyes are suspect carcinogens. Check that diazotisation is complete by testing for excess nitric(III) acid before
proceeding to the next reaction step. Where possible, prepare
water-soluble dyes such as methyl orange. See also Hazcard
4A.
3
-3
Add 1 g of sodium nitrite to 10 cm of ice-cold 1 mol dm
sulfuric(VI) acid. On warming, nitrogen oxides (TOXIC) are
produced.
-3
Solutions can explode if sufficiently concentrated.
For emergencies, see Hazcard E as well as more detailed information which may be on this Hazcard.
© CLEAPSS 2007