Water continued saturation index

A suite of both oxidized and reduced iron minerals has been found as efflorescences and precipitates in or near the acid mine water of Iron Mountain. The dominant minerals tend to be melan-terite (or one of its dehydration products), copiapite, jarosite and iron hydroxide. These minerals and their chemical formulae are listed in Table III from the most ferrous-rich at the top to the most ferric-rich at the bottom. These minerals were collected in air-tight containers and identified by X-ray diffractometry. It was also possible to check the mineral saturation indices (log Q(AP/K), where AP = activity product and K = solubility product constant)of the mine waters with the field occurrences of the same minerals. By continual checking of the saturation index (S.I.) with actual mineralogic occurrences, inaccuracies in chemical models such as WATEQ2 can be discovered, evaluated and corrected (19), provided that these occurrences can be assumed to be an approach towards equilibrium. 

The growth of calcite crystals to form speleothems is a delicately balanced process depending on the degree of supersaturation of the water and its total concentration of dissolved carbonates. Waters dripping onto speleothems require supersaturations on the order of Sk = +0.5 in order to overcome nucleation barriers (where Sic is the saturation index defined in the textbooks cited above). However, the critical supersaturation for 2-dimensional nucleation and the continued growth of a single ciystal is only slightly... 

Domestic or industrial hot-water heaters of galvanized steel through which hot aerated water passes continuously are not protected reliably in all types of water by nontoxic chemical additions such as silicates or polyphosphates. Adjustment of the saturation index to a more positive value, as discussed earlier, is sometimes helpful. Often, cathodic protection or use of nonferrous metals, such as copper or 70% Ni-Cu (Monel), is the best or only practical measure. 

Once-through cooling waters (usually obtained from rivers, lakes, or wells) usually cannot be treated chemically, both because of the large quantities of inhibitors required and because of the problem of water pollution. Sometimes, additions of about 2-5 ppm sodium or calcium polyphosphate are made to help reduce corrosion of steel equipment. In such small concentrations, polyphosphates are not toxic, but water disposal may continue to be a problem because of the need to avoid accumulation of phosphates in rivers and lakes. Adjustment of the saturation index to a more positive value is sometimes a practical possibility. Otherwise, a protective coating or metals more corrosion resistant than steel must be used. 

Dissolve 2.5 g of sodium hydroxide in 250 ml of water in a 500-ml two-necked flask fitted with a reflux condenser and a dropping funnel. Bring the solution to the boil, add rapidly from the dropping funnel 28.5 g (0.25 mol) of hexane-2, 5-dione (Expt 5.104) and continue to boil steadily under reflux for exactly 15 minutes (1). Cool the resulting dark-brown solution rapidly in an ice-salt bath, saturate with sodium chloride and extract with one 100 ml and two 50 ml portions of ether. Wash the ether extract with three 5 ml portions of water, dry over anhydrous sodium sulphate and remove the ether on a rotary evaporator. Distil the residual dark oil under reduced pressure and collect the colourless 3-methylcyclopent-2-enone as a fraction of b.p. 74-76 °C/ 16mmHg, n 0 1.4818 yield 9.5 g (40%). The product thus obtained is pure enough for most purposes when perfectly pure the refractive index is 1.4893. The product may darken on storage. 

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