On the Heat of Solution in Water and the Hydration Number of the Cobalt(III) Complexes at Infinite Dilution

Abstract

The heat of solution in water (endothermie)' and the hydration number, of twenty-six kinds of the cobalt( )cor 1exes andof ten: kinds of simple salts were determind at in nite dilution (250C) using micro calorimeter of twin-type and ultrasonic interferometer, respectively. The additive property held on both the heat of solution in water and the hydration number of the constituent ions. The hydrations number were as follows, Co(NHg)glg 11, [Co(H20)(NH3)g]S12, [Co(en)3]3' 14, [Co(NO2)(NHs)s]2 16, [CoCl(NH, )s]2 24, Co(COs)(NH3)'1 21, [Co(gly)s]26, [Co(edta)] 18, [Co(NO2)a NHs 2]ww 23, [Co N Os d]'S, pt 33, Na 5.1, K 8.4, NH 1.7, Clew 2.0, Br 4.3, lww 2.7, NOs 4.3. The heat of solution to 1 mole of hydrated water was.59 kcal for all the salts determined. h the case of cationic cobalt( )complexes, co plex ions with smaller electric charge had greater hydration numbers. For the complex ions with equal electric charge, the hydratidn numbers ef complexes tended to increase as an ionic radius of cationic complex inereased.