Ferric ammonium alum

Synonyms ferric ammonium sulfate ammonium ferric sulfate iron alum ferric alum ferric ammonium alum... 

The term alum, itself, refers to potassium alum, potassium aluminum sulfale, KA1(S04)2 12H O. Oilier common alums are ferric ammonium alum, NH4 Fe(S02)2 12HiO. and sodium chrome alum, NaCr(SOa)212ITO. 

Synonyms Ammonio-ferric alum, Ammonio-ferric sulfate, Ammonium sulfate, Ferric ammonium alum, Ferric ammonium sulfate, Ferric alum, Iron ammonia sulfate, Iron ammonium alum, Iron sulfate. 

Ferrous Ammonium Sulphate, FeS04-(NH4)2S04-6H20, and Ferric Ammonium Alum, Fe2(S04).r (NtL SCh H O, from Iron... 

Iron metal, wire III Q. 73 Ferric ammonium alum XI Ferric chloride II, III Ferric oxide XI... 

Potassium ferri-sulphite, KFe(S03)S04, is prepared by the action of potassium hydrogen sulphite upon ferric ammonium alum. It crystallises in slender needles, which are sparingly soluble in cold water. With hot water, ferrous and potassium sulphates pass into solution, leaving an insoluble yellow residue. 

Ammonium ferri-sulphite, NH4.Fe(S03)S04.H20, may be obtained by treating ferric ammonium alum with ammonium hydrogen sulphite. It crystallises in slender, yellow needles which are but slightly soluble in cold and hot water. Prolonged boiling decomposes the salt. 

Ammonium ferri-disulphate, NH4[Fe(S04)2], is prepared by heating a solution of ferric ammonium alum with sulphuric acid for some hours.3 It is a white crystalline powder, sparingly soluble in water. 

Ferric ammonium alum or Iron ammonium alum, (NH4)2S04. Fe2(S04)3.24H20, has been obtained by electrolysing a solution of ferrous sulphate and ammonium sulphate.3 The cathode consists of platinum wire immersed m acidified ferrous sulphate solution contained in a porous pot. An acidulated solution of ferrous and ammonium sulphates surrounds the pot, and is contained m a platinum dish which serves as anode. A current of 0-04 ampere is passed through the cell, and after several hours crystals of the alum are deposited round the anode. 

When ferric ammonium alum and potassium ferricyanide are acted upon with hydrogen peroxide in the presence of free hydrochloric acid, a blue substance, Fe7(CN)18.10H2O, is obtained, having properties similar to Williamson s violet, but less stable towards dilute ammonium hydroxide.7... 

About 2 gm. benzyl iodide are weighed into a flask and then 50 ml. 20% alcoholic potash solution are added and the mixture refluxed for about an hour. At the completion of the saponification the contents of the flask are allowed to cool and then transferred to a 500-ml. flask and made up to volume with water. 100 ml. of the resulting solution are placed in a distillation flask and distilled in steam after adding 10 gm. ferric ammonium alum and acidifying with sulphuric acid. By this treatment, the ferric salt is converted to the ferrous condition, liberating iodine which is distilled over into 5% potassium iodide solution. At the end of the distillation, the free iodine in the potassium iodide solution is titrated with a decinormal solution of sodium thiosulphate. From this, the amount of iodine and so the quantity of benzyl iodide in the sample may be calculated. 

They are isomorphous with one another, crystallize in octahedra, and are called alums. In the experiment described below ferric ammonium alum is prepared from ferrous sulphate and ammonium sulphate. The ferrous sulphate is first oxidized by means of nitric acid to ferric sulphate. 

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