Pentahydrates

This substance is familiar as the blue crystalline pentahydrate CUSO4.5H2O. In this crystal, each Cu ion is surrounded by four water molecules at the corners of a square, while the fifth water molecule is held by hydrogen bonds (see Figure 13.8). 

On heating the pentahydrate, four molecules of water are lost fairly readily, at about 380 K and the fifth at about 600 K the anhydrous salt then obtained is white the Cu " ion is now surrounded by sulphate ions, but the d level splitting energy does not now correspond to the visible part of the spectrum, and the compound is not coloured. Copper(Il) sulphate is soluble in water the solution has a slightly acid reaction due to formation of [CufHjOijOH] species. Addition of concentrated ammonia... 

Dissolve 3 g. of copper sulphate pentahydrate and 1 g. of sodium chloride in 12 ml. of hot water, and add a solution of 1 g. of sodium bisulphite in 10 ml. of 5 per cent, sodium hydroxide solution. Shake, cool under the tap, and wash the precipitated wlute cuprous chloride with water by decantation. Dissolve the cuprous chloride in a few ml. of concentrated ammonia solution and dilute with water to 10 ml. 

Mount a I litre bolt-head flask, fitted with a mechanical stirrer, on a water bath. Place 168 g. of powdered copper sulphate pentahydrate, 210 g. (214 ml.) of pyridine and 90 ml. of water in the flask, start the... 

By far the most commercially important boron compound in terms of dollar sales is Na2B407.5H20. This pentahydrate is used in very large quantities in the manufacture of insulation fiberglass and sodium perborate bleach. 

Solutions of Na2S203 are prepared from the pentahydrate and must be standardized before use. Standardization is accomplished by dissolving a carefully weighed portion of the primary standard KIO3 in an acidic solution containing an excess of KI. When acidified, the reaction between 103 and K... 

PORONCOMPOUNDS - BORON OXIDES, BORIC ACID AND BORATES] (Vol 4) Disodium tetraborate pentahydrate [12045-88-4]... 

Property MgSO, Kieserite Epsomite MgS0,-8H,0 Starkeyite Pentahydrate Hexahydrate... 

The use of sofid supports in conjunction with permanganate reactions leads to modification of the reactivity and selectivity of the oxidant. The use of an inert support, such as bentonite (see Clays), copper sulfate pentahydrate, molecular sieves (qv) (151), or sifica, results in an oxidant that does not react with alkenes, but can be used, for example, to convert alcohols to ketones (152). A sofid supported permanganate reagent, composed of copper sulfate pentahydrate and potassium permanganate (153), has been shown to readily convert secondary alcohols into ketones under mild conditions, and in contrast to traditional permanganate reactivity, the reagent does not react with double bonds (154). 

Other Compounds. Other compounds of technological iaterest iaclude deep green plutonium(IV) nitrate pentahydrate [61204-24-8] ... 

There is much discussion on the nature of the aluminum species present in slightly acidic and basic solutions. There is general agreement that in solutions below pH 4, the mononuclear Al " exists coordinated by six water molecules, ie, [ ( 20) ". The strong positive charge of the Al " ion polarizes each water molecule and as the pH is increased, a proton is eventually released, forming the monomeric complex ion [A1(0H)(H20) ]. At about pH 5, this complex ion and the hexahydrated Al " are in equal abundance. The pentahydrate complex ion may dimerize by losing two water molecules... 

All sodium metasibcate products (SIC No. 2819743) are given on a 100 wt % sodium metasibcate pentahydrate basis. 

Bulk production of United States Pharmacopeia (USP) and reagent grades is based on the reaction of sodium carbonate or hydroxide with an acidic iodide solution, typically hydriodic acid or a metal iodide. After removal of chemical impurities, the solution is filtered and concentrated. Evaporation gives the anhydrous Nal. Controlled cool-down produces either the dihydrate or the pentahydrate [81626-33-7]. 

---