Sodium sulfates

Sodium sulfate is an important heavy chemical in the chemical industry and is found in many mineral deposits. The world reserves are so large that with the present rate of consumption they are sufficient for several hundred years. In addition to extraction from natural sources, it is also produced in large quantities as a byproduct e.g. in the production of potassium salts, sodium chloride and borax and in chemical and metal producing processes. Dedicated manufacture e.g. from sodium chloride and sulfuric acid has become less important. 

The worldwide production of anhydrous sodium sulfate or Glauber s salt (Na2S04 IOH2O) in 1994 was 4.3 10 t/a, of which ca. 2.3 10 t/a was from natural deposits. It has decreased slightly in recent years due to a stagnation in consumption. 

The production of pure sodium sulfate or Glauber s salt Natural Na2S04  

Sodium sulfate is produced in large quantities as a byproduct in various chemical and metallurgical processes e.g. in the production of sodium dichromate, vitamin C, formic acid, resorcinol and viscose fibers. 

Sodium sulfate is also formed as a byproduct in the manufacture of hydrogen chloride by the reaction of sodium chloride with sulfuric acid at high temperatures (Mannheim process, Hargreaves process and the fluidized bed process). At the end of the I970 s the Mannheim process was used to produce about half of the sodium sulfate produced in Europe. However, these processes are hardly operated any more. 

Data reported for the protolysis constant of water in sodium sulphate media are listed in Table 5.35. The data are solely for a temperature of 25 °C, with the data being reported by Fischer and Bye (1964). 

Curti and Grambow (2005) have listed water activity data for sodium sulphate solutions. The dependence of the water activity data on the ionic strength for these solutions can be described using Eq. (5.19), and the values derived for and 2 r 0.03819 + 0.00078x10 and —(3.73 0.60)x 10 kgmol , respectively. 

On the basis of the ion interaction parameters determined for (Na , OH ) above, those for the interaction between (H, are 

Note the differing equation for the ion interaction coefficients because of the 2 1 electrolyte. Also, for this electrolyte, the ionic strength / is three times the medium concentration. In Eq. (5.17), the expression for D needs to include the Pitzer extension as given in Eq. (5.25)  

It is not clear why there is a need to modify the expression for D for electrolytes containing, at least, the sulphate anion. However, a good fit to the measured data cannot be obtained if the Pitzer extension to D is not used. 

---

Equation V-64 is that of a parabola, and electrocapillary curves are indeed approximately parabolic in shape. Because E ax tmd 7 max very nearly the same for certain electrolytes, such as sodium sulfate and sodium carbonate, it is generally assumed that specific adsorption effects are absent, and Emax is taken as a constant (-0.480 V) characteristic of the mercury-water interface. For most other electrolytes there is a shift in the maximum voltage, and is then taken to be Emax 0.480. Some values for the quantities are given in Table V-5 [113]. Much information of this type is due to Gouy [125], although additional results are to be found in most of the other references cited in this section. 

Fig. V-12. Variation of the integral capacity of the double layer with potential for 1 N sodium sulfate , from differential capacity measurements 0, from the electrocapillary curves O, from direct measurements. (From Ref. 113.)...

Endo-exo product mixtures were isolated using the following procedure. A solution of cyclopentadiene (concentration 2-10" M in water and 0.4 M in oiganic solvents) and the dienophile (concentration 1-5 mM) in the appropriate solvent, eventually containing a 0.01 M concentration of catalyst, was stirred at 25 C until the UV-absorption of the dienophile had disappeared. The reaction mixture (diluted with water in the case of the organic solvents) was extracted with ether. The ether layer was washed with water and dried over sodium sulfate. After the evaporation of the ether the... 

In a typical experiment 105 mg (0.50 mmol) of 3.8c, dissolved in a minimal amount of ethanol, and 100 mg (1.50 mmol) of 3.9 were added to a solution of 1.21g (5 mmol) of Cu(N03)2 BH20 and 5 mmol of ligand in 500 ml of water in a 500 ml flask. -Amino-acid containing solutions required addition of one equivalent of sodium hydroxide. When necessary, the pH was adjusted to a value of 5 ( -amino acids) and 7.5 (amines). The flask was sealed carefully and the solution was stirred for 2A hours, followed by extraction with ether. After drying over sodium sulfate the ether was evaporated. Tire endo-exo ratios were determined from the H-NMR spectra of the product mixtures as described in Chapter 2. 

Alkvl Azides from Alkyl Bromides and Sodium Azide General procedure for the synthesis of alkyl azides. In a typical experiment, benzyl bromide (360 mg, 2.1 mmol) in petroleum ether (3 mL) and sodium azide (180 mg, 2.76 mmol) in water (3 mL) are admixed in a round-bottomed flask. To this stirred solution, pillared clay (100 mg) is added and the reaction mixture is refluxed with constant stirring at 90-100 C until all the starting material is consumed, as obsen/ed by thin layer chromatographv using pure hexane as solvent. The reaction is quenched with water and the product extracted into ether. The ether extracts are washed with water and the organic layer dried over sodium sulfate. The removal of solvent under reduced pressure affords the pure alkyl azides as confirmed by the spectral analysis. ... 

With brisk stirring 75mL Everclear (ethanol) is poured into the reaction flask then 75mL concentrated sulfuric acid is slowly added until incorporated. The rest of the distillation apparatus is connected and the solution slowly heated to about 140°C. Next, 150mL Everclear is dripped in slowly so as to match the approximate distillation output that one can see condensing over into the collection flask. The temperature must remain between 140-150 C. After all the ethanol has been added (which should have taken approximately 90 min) the distillate that has collected is washed with 5% NaOH solution then with water (remember that the ether will form the top layer here). The ether can then be dried through sodium sulfate and used or can be distilled to purify. 

A solution of a-lithiomethoxyallene was prepared from nethoxyal lene and 0.20 mol of ethyllithiurn (note 1) in about 200 ml of diethyl ether (see Chapter II, Exp. 15). The solution was cooled to -50°C and 0.20 mol of ethylene oxide was added immediately. The cooling bath was removed temporarily and the temperature was allowed to rise to -15 c and was kept at this level for 2.5 h. The mixture was then poured into 200 ml of saturated ammonium chloride solution, to which a few millilitres of aqueous ammonia had been added (note 2). After shaking the layers were separated. The aqueous layer was extracted six times with small portions of diethyl ether. The combined ethereal solutions were dried over sodium sulfate and subsequently concentrated in a water-pump vacuum. Distillation of the... 

Galena, see Eead sulfite Glauber s salt, see Sodium sulfate 10-water Goethite, see Iron(II) hydroxide oxide Goslarite, see Zinc sulfate 7-water Graham s salt, see Sodium phosphate(l —) Graphite, see Carbon... 

Thenardite, see Sodium sulfate Thionyl, see Sulflnyl Thorianite, see Thorium dioxide Topaz, see Aluminum hexafluorosilicate Tridymite, see Silicon dioxide Troilite, see Iron(II) sulflde... 

Lehman, T. A. Everett, W. W. Solubility of Lead Sulfate in Water and in Sodium Sulfate Solutions, /. Chem. Educ. 1982, 59, 797. 

SODIUMCOMPOUNDS - SODIUM SULFATES] (Vol 22) -for hydrogen chloride fTYDROGEN Cm ORIDE] (Vol 13)... 

---