HCN - HYDROGEN CYANIDE

Properties of hydrogen cyanide:

Hydrocyanic acid. It is colorless light low boiling liquid; associated by hydrogen bonds (at room temperature the degree of association is equal to 2). There are two tautomeric forms: normal (H - C ≡ N :) and iso-shape (H - N ≡ C :); at 25 ° C in an equilibrium mixture of 0.5% iso-form, upon cooling amount of iso-form is reduced. Decomposes at high heat and on light. Unlimited mixed with water, shows weak acidic properties. In the concentrated solution is unstable and gradually decomposed with formation of ammonium formate (inhibitor - traces of sulfuric acid). Neutralized with an alkalis. Shows reducing properties; burns in air, it is reacts with halogens, concentrated sulfuric acid, nitrogen dioxide. Liquid HCN - is a polar proton solvent with high dielectric permeability.


Molar mass g/mol 27.03
Density g/cm3 0.699
Melting point °C -13.3
Boiling point °C 25.65

Methods for preparation of hydrogen cyanide:

2C + H2 + N2 = 2HCN (above 1800° C).

CO + NH3 = HCN + H2O (500-800° C, catalyst A2O3/ThO2).

KCN(solid) + HCl(conc., cold) = KCl + HCN↑.

2KCN + H2SO4(conc. 30%) = 2HCN↑ + K2SO4 (30-40° C).

KCN + H2O + CO2 = KHCO3 + HCN.


Chemical reactions with hydrogen cyanide:

HCN(diluted) + H2O(cold) = H3O(+) + CN(-),

HCN(conc.) + 2H2O = NH(+)4 + HCOO(-).

HCN + NaOH(conc.) = NaCN + H2O.

HCN + NH3 • H2O(conc.) = NH4CN + H2O (normal temp.).

HCN(gas) + H2O + H2SO4(conc.) = CO + NH4HSO4.

HCN + 4H0(Zn, diluted HCl) = CH3NH2.

4HCN + 5O2 = 4CO2 + 2N2 + 2H2O (burning on air),

4HCN + O2 = 2C2N2 + 2H2O (150° C, catalyst Ag).

HCN(solution) + Cl2 = (CN)Cl + HCl,

2HCN(gas) + Cl2 = C2N2 + 2HCl (catalyst - activated carbon),

HCN + H2O + Cl2 = HOCN + 2HCl (catalyst Al2O3).

2HCN + 5HClO = 2CO2↑ + H2O + N2↑ + 5HCl.

2HCN + NO2 = C2N2 + NO + H2O (normal temp.).


 

Did you know?

Chalk is made of trillions of microscopic skeleton fossils of plankton.