Ferrous sulphate, evaporation

When evaporating large amounts of impure ether which has been exposed to the air for a long time, the possibility of the occurrence of a violent explosion at the end of the evaporation, due to the presence of peroxides, must be taken Into account. Such ether has a pungent odour, and liberates iodine from an acid solution of potassium iodide. The peroxides can be destroyed by shaking with a weakly acid solution of ferrous sulphate. 

Ferric sulphate (XH2O) [10028-22-5] M 399.9 + XH2O. Dissolve in the minimum volume of dilute aqueous H2SO4 and allow to evaporate at room temp until crystals start to form. Do not concentrate by boiling off the H2O as basic salts will be formed. Various hydrates are formed the common ones are the dodeca and nona hydrates which are violet in colour. The anhydrous salt is colourless and very hygroscopic but dissolves in H2O slowly unless ferrous sulphate is added. 

Alkalies. —Add 5 cc. of nitric acid (sp. gr. 1.3) to a solution of 5 gra. of ferrous sulphate in 100 cc. of water, and boil for several minutes then add 15 cc. of ammonia water, filter, and evaporate the filtrate. The residue ignited should not exceed 0.001 gm. in weight. 

Detection of Potassium Nitrate.—About 5 grams of the extract (15 grams if liquid) are diluted with 20 c.c. of distilled water and the liquid mixed with 10 c.c. of 20% sulphuric acid and distilled, the distillate being collected in 10-20 cc. of a dilute sodium bicarbonate solution. The distillation is continued until the substance begins to bump, the distillate being then evaporated to small volume, acidified with dilute sulphuric acid and tested for nitric acid by means of ferrous sulphate or brucine in the usual way (see also p. 7). 

Procedure, ioo c.c. of the wine are evaporated in a flask to io c.c., allowed to cool and treated with 6 c.c. of the saturated ferrous sulphate solution and 4 c.c. of concentrated sulphuric acid.1 The flask is connected with a vertical condenser about 50 cm. long and heated carefully over a small flame so that excessive frothing of the mass is avoided. The distillate is collected in two or three well-cleaned tubes, each containing 2-3 c.c. of the iodide-starch paste acidified with 2 drops of dilute sulphuric acid the tubes are inclined so that the distillate flows down the walls. In presence of nitrites, a blue ring forms at the zone of separation between the starch and the distillate. 

Drainage water from coal mines is frequently charged with ferrous sulphate consequent upon the oxidation of pyrites in the coal, and upon evaporation yields the impure salt. The salt is readily obtained in a pure state by dissolving electrolytic iron in dilute sulphuric acid and allowing to crystallise, preferably in an inert atmosphere. Commercially ferrous sulphate is obtained by exposing heaps of pyrites to the oxidising action of the air. Ferrous sulphate and free sulphuric acid drain off into tanks, the acid being neutralised with scrap iron —... 

Ferrous nitrate may also be obtained in solution by grinding lead nitrate with an equivalent quantity of ferrous sulphate in the presence of dilute alcohol, double decomposition takes place, the ferrous nitrate passing into solution. Upon evaporation at room temperature the salt... 

Copper, Nitric Acid, etc. (Alkali Salts, Calcium). — Dilute 20 iM. of ferric chloride solution (1 1) with 100 cc. of water, fuld 25 cc. of ammonia water, and filter. On evaporating 50 cc. of the colorless filtrate and igniting the residue, the weight of the latter should not exceed 0.001 gm. On mixing 2 cc. of the filtrate with 2 cc. of concentrated sulphuric acid, and overlaying tliis mixture with 1 cc. of ferrous sulphate solution, no brown zone should form at the contact-surfaces of the two licpiids. 20 cc. of the filtrate acidulated With acetic a

potassium ferrocyanide solution. 

Crystallization by Concentration and Cooling.—There are very many cases in chemical manufacture where the desired product is produced as a practically pure water solution of the substance. This is especially true of metallic salts such as ferrous sulphate, copper sulphate, zinc sulphate, lead acetate, etc. The solutions of these salts are generally concentrated in open evaporators, usually... 

Ferric Sulphates are quite numerous, and are formed by oxidation of ferrous sulphate under different conditions. The normal sulphate, (FeJ (SO,), is formed by treating solution of FeSO, with HNO, and evaporating, after addition of one molecule of H,SO, for each two molecules of Fe, . The Liq. fer. tersulphiUie C. S.) contains this salt It is a yellowish-white, amorphous solid. 

Characters and Tests.—Colourless liquid. Sp. gr. 1 42 boiling-point 250 F. Exposed to air, it emits acrid and corrosive fumes. Copper dropped into a mixture of equal parts of the add and water causes the evolution of a colourless gas (nitric oxide), which, as it mixes with the oxygen of the air, forms ruddy fumes (nitric trioxide and nitric peroxide). A crystal of ferrous sulphate dropped into the add, diluted with an equal bulk of water, becomes surrounded by a brown cloud if the mixture be cold. The add should leave no residue on evaporation. Diluted with six times its volume of distilled water, it should give no precipitate with barium nitrate or silver nitrate, showing the absence of sulphuric and hydrochloric acids. 

Characters and Tests.—Colourless, heavy, oily, intensely acid liquid. Sp. gr. 1 843. Mixed with water, much heat is evolved. Diluted with five or six times its volume of water, it gives, with barium chloride, a white precipitate (barium sulphate), which is insoluble in nitric acid it should yield no precipitate or darkening of colour with hydrosulphuric acid, indicating the absence of lead. When a solution of ferrous sulphate is carefully poured upon the sur ce of the acid, there should be no brown colour developed where the two liquids unite, showing the absence of nitric acid and oxides of nitrogen. The acid should leave no residue on evaporation. 

Henry prepared sodium and potassium bromides by boiling ferrous bromide respectively with potassium or sodium carbonate until the precipitate is brown the clear liquid was then filtered and evaporated. J. Knobloch recommended treating a mixture of ferrous bromide with milk of lime, and then with potassium sulphate if potassium bromide is desired, or with Glauber s salt if sodium bromide is to be made. The mixture is then to be boiled, the precipitated iron oxide filtered off, and the soln. evaporated, for cubic crystals of potassium bromide. This is the principle of the method employed for manufacturing potassium bromide on a large scale ... 

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