Sodium dihydrogen phosphate, also known as acidic sodium phosphate, has the molecular formula of NaH2PO4·2H2O and NaH2PO4, and the relative molecular masses are 156.01 and 119.98. An anhydrate and a dihydrate, the dihydrate is a colorless to white crystal or a crystalline powder, and the anhydrate is a white powder or granule. Soluble in water, almost insoluble in ethanol. When the crystal water is lost at 100 ° C and heating is continued, acid sodium pyrophosphate is formed.
CAS No.: 7558-80-7
Chemical formula and relative molecular mass: NaH2PO4: 119.98 g/mol
colorless crystal or white crystalline powder. Odorless, salty, sour. Heated to 100 ° C lost all of the water of crystallization, burning into sodium metaphosphate. Soluble in water, almost insoluble in ethanol, its aqueous solution is acidic. The pH of the 0.1 mol/L aqueous solution at 25 ° C was 4.5. The relative density is 1.915. The temperature of 60 ° C. The product also has a molecule of crystal water.
Uses: granules. Softener. Production of sodium hexametaphosphate and sodium pyrophosphate. Determination of magnesium. A modified white medium was prepared in a single sports species.
Quality index
Arsenic (As), % ≤ 0.0002
ammonium (NH4), % ≤ 0.002
ammonia precipitate , % ≤ 0.01
pH (50g / L, 25 ° C) 4.2 ~ 4.6
water insoluble matter, % ≤ 0.01
heavy metal (in Pb) , % ≤ 0.001
potassium (K), % ≤ 0.02
iron (Fe), % ≤ 0.001
chloride (Cl), % ≤ 0.005
sulfate (SO4), % ≤ 0.005
nitrate (NO3), % ≤ 0.001
clarity test Qualified
content (NaH2PO4·2H2O), % ≥99.0
Density 1.949/cm. The temperature of 60 ° C. There are three kinds of water, one water and two water. The anhydrate is a white crystalline powder which is slightly hygroscopic and highly soluble in water. Anhydrous is a colorless orthorhombic crystal, easily soluble in water, and the aqueous solution is acidic (pH=4.5), insoluble in alcohol, and slightly soluble in chloroform. Dihydrate is also very soluble in water, easy to agglomerate in humid air, dehydrated to anhydrous at 100 ° C, sodium pyrophosphate formed at 190-210 ° C, and decomposed into sodium metaphosphate at 280-300 ° C. The aqueous solutions are all acidic. At present, the product is mainly dihydrate. At a certain pH, it is prepared by reacting sodium carbonate with phosphoric acid or by reacting disodium hydrogen phosphate with a certain proportion of phosphoric acid, and is easy to agglomerate in humid air.
Uses: Used in boiler water treatment, electroplating, tanning, baking powder, fuel additives, detergents, mica and gelatin, acid retardant, etc. It is also the raw material for preparing sodium hexametaphosphate and polycondensate.
