KCN - POTASSIUM CYANIDE

Properties of potassium cyanide:

White, thermally stable, melt without decomposition. It is readily soluble in water (strong hydrolysis on the anion). Doesn't form crystalline hydrates. At storage of the concentrated solution slowly decays. It reacts with acids. It absorbs moisture and CO2 from the air. Attaches oxygen, sulfur. Reducing agent. Participates in reactions of an exchange and complex formation.


Molar mass g/mol 65.12
Density g/cm3 1.52
Melting point °C 634.5

Methods for preparation of potassium cyanide:

KOH(conc.) + HCN = KCN + H2O.

K2CO3 + C(coke) + CaCN2 = 2KCN + CaCO3 (900° C).

KNH2 + NH4Cl = 2NH3 + KCl (-40° C, in liquid NH3).


Chemical reactions with potassium cyanide:

KCN(diluted) + 6H2O(cold) = [K(H2O)6](+) + CN(-).

KCN + 2H2O = NH3↑ + K(HCOO) [boiling.].

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

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

KCN + H2O + CO2 = KHCO3 + HCN.

2KCN(diluted, cold) + O2 = 2KOCN (catalyst Ni).

KCN(diluted) + S = KNCS (boiling).

KCN + K2S4O6 + H2O = KNCS + K2SO3S + H2SO4.

KCN(conc.) + E2 = (CN)E + KE (E = C, Br, I),

(CN)Cl + KF = (CN)F + KCl (700◦ C).

KCN + H2O2(conc. 30%) = KOCN + H2O.

KCN + PbO = Pb + KOCN (400-500° C).

KCN + 2KOH(conc.) + 2KMnO4 = KOCN + 2K2MnO4 + H2O.

2KCN + H2O + 5KClO = 2KHCO3 + 5KCl + N2↑.

2KCN(conc.) + AgNO3 = K[Ag(CN)2] + KNO3.

8KCN(conc.) + Au2S3 = 2K[Au(CN)4] + 3K2S.

2KCN(diluted) + NiSO4 = Ni(CN)2↓ + K2SO4,

2KCN(conc.) + Ni(CN)2 = K2[Ni(CN)4].

6KCN(diluted) + 2FeCl3 = (Fe(3+))[Fe(CN)6] + 6KCl,

6KCN(conc.) + FeCl3 = K3[Fe(CN)6] + 3KCl.


 

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Elements in horizontal rows are called periods.