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Sodium sulfate - Wikipedia, the free encycloped <br />Physical and chemical properties <br />Sodium sulfate is chemically very stable, being unreactive toward most <br />oxidising or reducing agents at normal temperatures. At high <br />temperatures, it can be reduced to sodium sulfide:l41 <br />Na2SO4 + 2 C —> 2 Na2S + 2 CO2(9) <br />Sodium sulfate is a neutral salt, which forms aqueous solutions with pH of <br />7. The neutrality of such solutions reflects the fact that Na2SO4 is derived, <br />formally speaking, from the strong acid sulfuric acid and a strong base <br />sodium hydroxide. Sodium sulfate reacts with an equivalent amount of <br />sulfuric acid to give an equilibrium concentration of the acid salt sodium <br />bisulfatel51161: <br />Na2SO4(aq) + H2SO4(aq) 1�:t 2 NaHSO4(aq) <br />In fact, the equilibrium is very complex, depending on concentration and <br />temperature, with other acid salts being present. <br />Sodium sulfate is a typical ionic sulfate, containing Na+ ions and S042 <br />ions. Aqueous solutions can produce precipitates when combined with <br />salts of Bat+ or Pb2+, which form insoluble sulfates <br />!>o <br />50 <br />8 <br />40 <br />I <br />Na2SO4(aq) + BaCh(aq) —> 2 NaCI(aq) + BaSO4(s) <br />Solubility of Sodium Sulfate vs. Temperature <br />Sodium sulfate has <br />unusual solubility <br />characteristics in <br />water.l71 Its solubility <br />in water rises more than <br />tenfold between 0 °C to <br />32.384 °C, where it <br />zo reaches a maximum of <br />10 <br />_ 497 g/L. At this point <br />0 _ the solubility curve <br />C so ,pp 150 2w changes slope, and the <br />T—P.. — rcl solubility becomes <br />almost independent of <br />temperature. This temperature at 32.384 °C, corresponding to the release <br />of crystal water and melting of the hydrated salt, serves as an accurate <br />temperature reference for thermometer calibration. <br />http://en.wildpedia.orgtwild/Sodium sulfate <br />Refractive index <br />1.468 (anhydrous) <br />11.394 <br />(nD) <br />(decahydrate) <br />Structure <br />Crystal structure <br />orthorhombic or hexagonal <br />(anhydrous) <br />monoclinic (decahydrate) <br />Hazards <br />MSDS <br />External MSDS <br />EU Index <br />Not listed <br />Main hazards <br />Irritant <br />NFPA 704 <br />0 <br />Flash point <br />Non-flammable <br />Related <br />compounds <br />Other anions <br />Sodium selenate <br />Sodium tellurate <br />Other cations <br />Lithium sulfate <br />Potassium sulfate <br />Rubidium sulfate <br />Caesium sulfate <br />Related <br />Sodium bisulfate <br />compounds <br />Sodium sulfite <br />Sodium persulfate <br />Supplementary data page <br />Structure and <br />n, sr, etc. <br />properties <br />Thermodynamic <br />Phase behaviour <br />data <br />Solid, liquid, gas <br />Spectral data <br />UV, IR, NMR, MS <br />,/(what is this?) (verify) <br />Except where noted otherwise, data are given for <br />materials in their standard state (at 25 °C, 100 kPa) <br />Info box references <br />Sodium sulfate decahydrate is also unusual among hydrated salts in having a measureable residual entropy (entropy at <br />absolute zero) of 6.32 J -K 1 -mol 1. This is ascribed to its ability to distribute water much more rapidly compared to most <br />hydrates.l81 <br />Sodium sulfate displays a moderate tendency to form double salts. The only alums formed with common trivalent metals are <br />NaAI(SO4)2 (unstable above 39 °C) and NaCr(SO4)2, in contrast to potassium sulfate and ammonium sulfate which form <br />many stable alums.191 Double salts with some other alkali metal sulfates are known, including Na2SO4.3K2SO4 which occurs <br />naturally as the mineral glaserite. Formation of glaserite by reaction of sodium sulfate with potassium chloride has been used <br />as the basis of a method for producing potassium sulfate, a fertiliser.) lo] Other double salts include 3Na2SO4-CaSO4, <br />3Na2SO4-MgSO4 (vanthoffite) and NaF-Na2SO4.111] <br />2 of 4/16/20119:24 PM <br />