Determination of Equilibrium Constants for Reactions between Nitric Oxide and Ammoniacal Cobalt(II) Solutions at Temperatures from 298.15 to 309.15 K and pH Values between 9.06 and 9.37 under Atmospheric Pressure in a Bubble Column

2013-03-13T00:00:00Z (GMT) by Hesheng Yu Zhongchao Tan
Experiments were conducted in a bubble column to determine the equilibrium constants of reactions between NO and ammoniacal cobalt­(II) solutions at temperatures between 298.15 and 310.15 K and pH values from 9.06 to 9.37 under atmospheric pressure. The two reactions are 2Co­(NH3)5(H2O)2+ + 2NO ⇌ (NH3)5Co­(N2O2)­Co­(NH3)54+ + 2H2O and 2Co­(NH3)62+ + 2NO ⇌ (NH3)5Co­(N2O2)­Co­(NH3)54+ + 2NH3, respectively. Their equilibrium constants are calculated on the fraction molar basis. All experimental data fit well to the equations ln KNO5 = 3598.5­(1/T) + 16.759 and ln KNO6 = 1476.4­(1/T) + 26.597, which give the enthalpy of reactions between NO and penta- and hexaamminecobalt­(II) nitrates: ΔrH5° = −29.92kJ·mol–1 and ΔrH6° = −12.27kJ·mol–1.