Copper 2, pentahydrate

ClgHanCuNioOi2 0.75 NH4CIO4, Diammonium aqua(hexamethyldioxaocta-azatricycloeicosatetronato)copper (2+) pentahydrate ammonium perchlorate, 42B, 840... 

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... 

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). 

Hypobromites, the salts of hypobromous acid, do not keep well because they gradually disproportionate to bromide and bromate. Solutions are best prepared as needed from bromine and alkafl with cooling. Because disproportionation is catalyzed by cobalt, nickel, and copper (70), these impurities should be avoided. SoHd alkaline earth hypobromites, or more properly, bromide hypobromites such as calcium bromide hypobromite [67530-61 CaBr(OBr), have been known for many years, but the pure crystalline hydrates sodium hypobromite pentahydrate [13824-96-9] NaOBr 5H20, and potassium hypobromite tribydrate [13824-97-0], KOBr 3H20, were not described until 1952 (71). Hypobromites are strong bleaching agents, similar to hypochlorites. 

Gopper(II) Sulfates. Copper(II) sulfate pentahydrate [7758-99-8] CuS04-5H20, occurs in nature as the blue triclinic crystalline mineral chalcanthite [13817-21 -5]. It is the most common commercial compound of copper. The pentahydrate slowly effloresces in low humidity or above 30.6°C. Above 88°C dehydration occurs rapidly. 

Copper(II) sulfate monohydrate [10257-54-2] CuS04-H2 0, which is almost white in color, is hygroscopic and packaging must contain moisture barriers. This product is produced by dehydration of the pentahydrate at 120—150°C. Trituration of stoichiometric quantities of copper(II) oxide and sulfuric acid can be used to prepare a material of limited purity. The advantages of the monohydrate as opposed to the pentahydrate are lowered freight cost and quickness of solubilization. However, these advantages are offset by the dustiness of the product and probably less than one percent of copper sulfate is used in the monohydrate form. 

Anhydrous copper(II) sulfate [7758-98-7] is a gray to white rhombic crystal and occurs in nature as the mineral hydrocyanite. CuSO is hygroscopic. It is produced by careful dehydration of the pentahydrate at 250°C. An impure product can also be produced from copper metal and hot sulfuric acid ... 

ChemicalDesignations-Synonym Blue Vitriol Copper Sulfate Pentahydrate Cupric Sulfate Sulfate of Copper Chemical Formula CuS04-5Hj0. 

Dialing solution Dissolve 1.5 g copper(II) sulfate pentahydrate in a few milliliters of water and make up to 100 ml with methanol. 

Tanimoto, A.K., Kobayashi, K. and Fujita, S., 1964. Overall crystallization rate of copper sulfate pentahydrate in an agitated vessel. International Chemical Engineering, 4(1), 153. 

Ionic compounds often separate from water solution with molecules of water incorporated into the solid. Such compounds are referred to as hydrates. An example is hydrated copper sulfate, which contains five moles of H20 for every mole of CuS04. Its formula is CuS04- 5H20 a dot is used to separate the formulas of the two compounds CuS04 and H20. A Greek prefix is used to show the number of moles of water the systematic name of CuS04- 5H20 is copper(ll) sulfate pentahydrate. 

Procedure. Dissolve 0.0393 g of pure copper(II) sulphate pentahydrate in 1 L of water in a graduated flask. Pipette 10.0 mL of this solution (containing about 100 jug Cu) into a beaker, add 5.0 mL of 25 per cent aqueous citric acid solution, render slightly alkaline with dilute ammonia solution and boil off the excess of ammonia alternatively, adjust to pH 8.5 using a pH meter. Add 15.0mL of 4 per cent EDTA solution and cool to room temperature. Transfer to a separatory funnel, add lOmL of 0.2 per cent aqueous sodium diethyldithiocarbamate solution, and shake for 45 seconds. A yellow-brown colour develops in the solution. Pipette 20 mL of butyl acetate (ethanoate) into the funnel and shake for 30 seconds. The organic layer acquires a yellow colour. Cool, shake for 15 seconds and allow the phases to separate. Remove the lower aqueous... 

A typical thermogravimetric curve, for copper sulphate pentahydrate CuS04,5H20, is given in Fig. 11.2. 

As Fig. 11.2 shows, copper sulphate pentahydrate has four distinct regions of decomposition ... 

Experimental factors. In the previous section it was stated that the precise temperature regions for each reaction of the thermal decomposition of copper sulphate pentahydrate is dependent upon experimental conditions. When a variety of commercial thermobalances became available in the early 1960s it was soon realised that a wide range of factors could influence the results obtained. Reviews of these factors have been made by Simons and Newkirk30 and by Coats and Redfern31 as a basis for establishing criteria necessary to obtain meaningful and reproducible results. 

The heating rate has only a small effect when a fast reversible reaction is considered. The points of inflexion B and C obtained on the thermogravimetric curve for copper sulphate pentahydrate (Fig. 11.2) may be resolved into a plateau if a slower heating rate is used. Hence the detection of intermediate compounds by thermogravimetry is very dependent upon the heating rate employed. 

Notes. (1) Copper sulphate pentahydrate is suitable for practice in this determination 0.4 g of this contains about 0.1 g of Cu. 

Ng et al. [1261] report that dehydration of copper sulphate pentahydrate (- CuS04 3 H20) 320—336 K, obeys the Avrami—Erofe ev equation [eqn. (6), n = 2] with E = 104 kj mole-1. Dehydration of the trihydrate (- CuS04 H20), 343.5—359 K, obeyed the same rate expression with E = 134 kJ mole 1. Activation energies are approximately equal to reaction enthalpies. 

FIGURE D.l Blue crystals of copper(ll) sulfate pentahydrate (CuS04 5H20) lose water above 150°C and form the white anhydrous powder (CuS04) seen in this petri dish. The color is restored when water is added and, in fact, anhydrous copper sulfate has such a strong attraction for water that it is usually colored a very pale blue from reaction with the water in air. 

E.8 Copper metal can be extracted from a copper(II) sulfate solution by electrolysis (as described in Chapter 12). If 29.50 g of copper(II) sulfate pentahydrate, CuS04-511,0, is dissolved in 100. mL of water and all the copper is electroplated out, what mass of copper would be obtained ... 

Suppose we were asked to prepare 250. mL of a solution that was approximately 0.0380 M CuS04(aq) from solid copper(II) sulfate pentahydrate, CuS04-5H20. What mass of the solid do we need ... 

Then, because the molar mass of copper(II) sulfate pentahydrate is 249.6 g-mol this amount of the pentahydrate corresponds to the following mass, t c.us04-5H2o ... 

We conclude that we should measure out about 2.37 g of copper(II) sulfate pentahydrate. In practice, we might find that we had spooned out 2.403 g, in which case the molarity would be 0.0385 M CuS04(aq). 

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