Ammonium chloride

 

Ammonium chloride
aka Sal ammoniac

Chemical formula	NH4Cl
OTP appearance	white/clear crystals
Index of refraction	1.642
Molar Mass(g/mol)	53.49
Density(g/cc)	1.5274
Melting Point(°C)	338(decomp)
Boiling Point(°C)	520
Solubility in water(g/L)	383
Solubility in ethanol(g/L)	4.25
Solubility in methanol(g/L)	23.7
Solubility in ether(g/L)	insoluble
Solubility in acetone(g/L)	sparingly
NFPA 704	0 2 0

Uses

Other

• Feedstock for methylamine
• Precursor for copper (II) chloride, precursor for sulfuric acid
• Frigorific mixture component
• Flux for soldering
• Pharm: expectorant
• electrolyte in many voltaic cells

Natural occurrence

• Does occur naturally as the mineral sal ammoniac

Production

Synthesis

via sodium chloride

Bubble carbon dioxide through a solution of sodium chloride, ammonia, and water, producing ammonium chloride and sodium bicarbonate:

NaCl(aq) + NH₃(aq) + H₂O(l) + CO₂(g) → NaHCO₃(s) + NH₄Cl(aq)

1. Prepare an ammonia solution with a density of 0.907 (25% w/w) at 20°C
2. Heat the solution to 40°C
3. Add an excess of Salt
4. Decant/filter solution
5. Discard residue (undissolved salt)

   Solution is NH₄OH + NaCl + NH₄Cl + NaOH

6. Chill to -11°C
7. Precipitate is ammonium chloride (Approximately 10% w/w of the saturated salt solution)
8. Solution is NH₄OH + NaCl + NaOH with some remaining dissolved ammonium chloride, and weighs approximately 90% of the original saturated salt solution.

via hydrochloric acid

Combine ammonia and hydrochloric acid

NH₃ + HCl → NH₄Cl

via calcium chloride

(or magnesium chloride)

1. Bubble carbon dioxide through a solution of ammonia and magnesium or calcium chloride, precipitating magnesium or calcium carbonate:

   2 NH₃ + CaCl₂ + H₂O + CO₂ → 2 NH₄Cl + CaCO₃

2. Filter
3. Discard residue
4. Evaporate filtrate to crystallize ammonium chloride

Purification

Sublimation/dissociation

This could also replace the evaporation iterations in the synthesis. Ammonium chloride dissociates (reversibly) into ammonia and hydrogen chloride at 337.6 °C. If the gasses are cooled on a surface, they react to re-form ammonium chloride, so placing a cold boiling flask over a beaker of solid ammonium chloride, then heating the beaker would transport just the ammonium chloride to the bottom of the flask.

See Also

• US patent 2209681 "Electrolysis of ammonium chloride"
  Link courtesy Google
• US patent 2622004 "Cyclic process for production of sodium bicarbonate and ammonium chloride"
  Link courtesy Google