Mass spectrometric study of potassium cyanate and potassium cyanate - potassium cyanide system at high temperatures

Abstract

Vaporization of KCNO (over the temperature range 656 - 799 K) and of KCN - KCNO system (639 - 787 K) have been investigated by the Knudsen cell - mass spectrometric technique. Enthalpies of vaporization of monomeric and dimeric molecules have been determined as 187.3 ± 4.3 kJ/mol and 210.3 ± 4.6 kJ/mol, respectively. Partial pressures over the salt have been expressed as: log p(KCNO)/Pa = - (9 781 ± 222)/ T + (11.133 ± 0.119) log p(K 2(CNO) 2)/Pa = - (10 983 ± 240)/ T + (11.888 ± 0.091) Appart from vaporization, decomposition of KCNO to KCN and O 2 proceeds in some extent. The KCN - KCNO melt vaporizes as KCN, KCNO, K 2(CN) 2, K 2(CNO) 2, and K 2(CN)(CNO) molecules. The activities and vapor pressures of components have been determined over the melt composition range 0< x KCN< 0.632.