Properties of Ammonium bifluoride [NH4.HF2]

Ammonium bifluoride [NH4.HF2]

Properties of NH4HF2

Formula mass : 57.04
Melting point :124.6°C (Sublimes at higher temperature) 
Boiling point : 239.5°C
When dissolved in water, cooling takes place. Material is Hygroscopic at 50% humidity.

Analysis

Appearance : White crystalline solid (Orthorhombic crystals) 

NH4HF2 :  98.76%*
(NH4)2SO4 : 0.05%
(NH4)2SiF6  :0.20%
Moisture  :0.59%

Solubility in water  : 60.2 g at 20°C and 156.4g at 60°C per 100ml of water
Solubility in HCl  :  10% (w/v) sample is soluble in 15% (w/w) of HCl at 25°C

*Assay: Weigh accurately about 1.0gm of Ammonium bi fluoride sample. Dissolve it in 100ml distilled water. Titrate with about 1N NaOH. Use Phenolphthalein as indicator. End point is Colourless to Pink. 

% acidity as HF =  A / B

1st calculate Consumption of NaOH, B.R. X  Normality of NaOH X  0.02 X 100  = A
Then Divided the result with " Weight of the sample "   = B

%NH4HF= %acidityasHFx57 /  20

 

*Assay: Weigh accurately about 1.0gm of Ammonium bi fluoride sample. Dissolve it in 100ml distilled water. Titrate with about 1N NaOH. Use Phenolphthalein as indicator. End point is Colourless to Pink.

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