Theoretically the reaction takes place in the case of ferric nitrate in the manner represented by the equation Fe(NOs) 3 + 3KCNS = Fe(CNS) 3 + 3KNOs; Ferric nitrate.
But it is found that even when more than sixty times the amount of potassium thiocyanate required by this equation is added, a portion of the ferric nitrate still remains unconverted, doubtless owing to the occurrence of the reverse change Fe (CNS) 3 +3KNOs =Fe(N03) 3+3KCNS.
Aniline combines directly with alkyl iodides to form secondary and tertiary amines; boiled with carbon disulphide it gives sulphocarbanilide (diphenyl thio-urea), CS(NHC 6 H 5) 2, which may be decomposed into phenyl mustard-oil, C 6 H 5 CNS, and triphenyl guanidine, C 6 H 5 N: C(NHC6H5)2.
This "passivity" may be brought about by immersion in other solutions, especially by those containing such oxidizing anions as NO' 3, C10' 3, less strongly by the anions SO" 4, CN', CNS', C2H30'2, OH', while Cl', Br' practically inhibit passivity; H' is the only cation which has any effect, and this tends to exclude passivity.
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