Na2MoO4,2H2O -- 241.9 -- 10102-40-6
DEFINITION
Content: 98.0 per cent to 100.5 per cent (dried substance).
CHARACTERS
Appearance: White or almost white powder or colourless crystals.
Solubility: Freely soluble in water.
IDENTIFICATION
A. Loss on drying (see Tests).
B. Dissolve 0.2 g in 5 ml of a mixture of equal volumes of nitric acid and water and
add 0.1 g of ammonium chloride. Add 0.3 ml of disodium hydrogen phosphate solution
and heat slowly at 50-60C. A yellow precipitate is formed.
C. Dissolve 0.15 g in 2 ml of water, the solution gives reaction of sodium.
TESTS
Solution S: Dissolve 10.0 g in water and dilute to 50 ml with the same
solvent.
Appearance of solution: Solution S is clear and colourless.
Chlorides: Maximum 50 ppm.
Phosphates: Maximum 200 ppm.
Ammonium: Maximum 10 ppm, determined on 0.10 g.
Heavy metals: Maximum 10 ppm.
Loss on drying: 14.0 per cent to 16.0 per cent, determined on 1.000 g by
drying in an oven at 140C for 3 h.
ASSAY
Dissolve 0.100 g in 30 ml of water, add 0.5 g of hexamethylenetetramine and 0.1 ml
of a 250 g/l solution of nitric acid. Heat to 60C. Titrate with 0.05 M lead nitrate
using 4-(2-pyridylazo)resorcinol monosodium salt as indicator.
1 ml of 0.05 M lead nitrate is equivalent to 10.30 mg of Na2MoO4.
