Sulfate Penta-Hydrate

Simple 1,2-dithiepanes are prepared by the oxidation of, -alkanedithiols using hydrogen peroxide, iodine, oxygen, or other oxidants . For example, potassium permanganate adsorbed on copper sulfate penta-hydrate oxidizes 1,5-pentanedithiol into 1,2-dithiepane 198 <1998S1587>. 

TABLE 11.2. Unit cell dimensions and atomic coordinates for copper sulfate penta-hydrate, CuS04-5H2 0 (Refs. 8 and 9). 

In contrast to the group II hydroxides, compounds containing so-called water of crystallization can be readily dehydrated. Eq. (3) represents the reactions reported for copper sulfate penta-hydrate heated at atmospheric pressure (7). 

Other oxy-salts loose water of hydration in a stepwise sequence when heated. Copper sulfate penta-hydrate loses water of hydration in three steps with the trihydrate as the intermediate. Such studies are of importance for differentiating between coordinated water and water of hydration. 

Copper-coated poly-p-phenylene terephthalamide fibers and films were prepared by the following procedure. The fibers and films were immersed in a solution of 0.1 a K+-CH2S (0)CH3 in DHSO for several seconds at room temperature and then into a solution of 0.1 U silver trifluoroacetate for several seconds at room temperature. The fibers and films were rinsed with water and dried by means of a vacuum. The fibers and films were then immersed for several seconds into a copper electroless plating bath consisting of 22.7 g of copper sulfate penta-hydrate, 12.5 g of sodium carbonate, 70.0 g of sodium potassium tartrate, and 9.0 g of ethylene diamine tetraacetic acid all in 400 mL of deionized water to which was added a Solution of 20.0 g of sodium hydroxide in 100 mL Of water and 65 mL of a 37% formaldehyde solution. The fibers and films were then rinsed with water and dried. 

Thiosulfate solutions are generally prepared from sodium thiosulfate penta-hydrate, NajSjOa SHjO, which under ordinary conditions is not a primary standard. The solutions should be prepared from water free of heavy-metal impurities to avoid catalytic air oxidation. Ordinary air oxidation is negligible in rate and proceeds through the slow decomposition of thiosulfate to sulfite, which is rapidly air-oxidized to sulfate. Catalyzed air oxidation, on the other hand, proceeds through the reduction of metals such as copper(II) or iron(III), present as thiosulfate complexes, followed by air oxidation of the lower oxidation state ... 

If one heats the blue copper sulfate solution until the dry blue copper penta hydrate salt (CuS04 5 H20) remains, the complex is still in the ionic lattice, this time, the central ion with four H20 ligands and two O atoms from surrounding sulfate ions (see Fig. 9.2). The fifth I IzO is not attached to the cation, it is held between water molecules attached to cations and O atoms of sulfate ions [2] (see Fig. 9.3). Furthermore, if one heats the blue salt the crystals turn into a white substance H20 molecules leave the complexes and an ionic lattice remains with the arrangement of copper ions and sulfate ions. 

The equilibrium pressure of the system can vary because we do not cany out the same reaction at all water pressures it is the case of copper sulfate. Indeed, we noted (section 3.8) that according to the range of pressure, we could carry out different dehydrations. Thus from penta-hydrated copper sulfate, we produce monohydrate for pressures lower than 40 Pa, that is, we ejqness the reaction ... 

Just as in binary molecular compounds, prefixes are used to indicate the number of water molecules in a formula unit of a hydrate (see Table 6.1). By this system, CUSO4 5 H2O is called copper(II) sulfate pentahydrate, since penta- is the prefix for 5. 

---