A Text-Book of Inorganic Chemistry, Descriptive, Theoretical, and Practical; A Manual for Advanced Students - Softcover
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt: ...+ 4 H2S04 = K2S04 + Cr2(S04)3 + 4 H20 + 3 0. The dichromate is nearly always used with sulfuric acid when used as an oxidizer. Its action towards such reducing agents as hydrogen sulfid and sulfur dioxid has already been examined in the last experimental study. The dichromate is changed to the normal chromate by an alkali; or, on the other hand, a chromate is changed to a dichromate by such acids as sulfuric and nitric acids. Alkali carbonates are decomposed by the dichromates, with the formation of the normal chromate. The dichromate is the source of all the other compounds of the metal. The useful chromium sulfate and its alum are generally waste products of some process in which the dichromate is used. When the dichromate is dissolved in hydrochloric acid, the compound undergoes a change that explains, in part, the for mation of the chromyl chlorid (Cr02Cl2). A compound is formed that contains chlorin, having the composition:--/0K Cr0/, or KCr03Cl, called potassium chlor-chromate. KA-A + 2 HCl = 2 KCr03Cl + H20. When this compound is treated with potassium hydroxid, the following reaction occurs:--/0K /0K Cr0a + K0H = Cr02 +KCl. Cl 0K This compound, the chlor-chromate, is therefore intermediate between chromyl chlorid and the normal chromate. Potassium dichromate is used in large quantities for batteries, in dyeing and calico-printing, in photogravure, and as an oxidizing agent in manufacturing and laboratory processes. Several million pounds of the dichromate are used in the United States alone annually. Potassium Chromate (K2Cr04).--Potassium chromate is typical of the alkali chromates. It is a yellow crystalline compound without water of crystallization. It is produced from the dichromate by treating it with an alkali or an alkali carbonate. Na2C03 + ...
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