Sodium sulfate deliquescence

Substances that are ordinarily deliquescent are sulfuric add (concentrated), glycerol, calcium chloride crystals, sodium hydroxide (solid), and 100% ethyl alcohol. In an enclosed space, these substances deplete the water vapor present to a definite degree. Other substances are used to accomplish this end by chemical reaction, e.g.. phosphorus pentoxide (forming phosphoric acid), and boron trioxide (forming boric acid). Water is absorbed from nonmiscible liquids by addition of such substances as anhydrous sodium sulfate, potassium carbonate, anhydrous calcium chloride. and solid sodium hydroxide. The converse phenomenon is known as efflorescence. 

Loss of water usually causes a breakdown in the structure of the crystal this is commonly seen with sodium sulfate, whose vapor pressure is sufficiently large that it can exceed the partial pressure of water vapor in the air when the relative humidity is low. What one sees is that the well-formed crystals of the decahydrate undergo deterioration into a powdery form, a phenomenon known as efflorescence. When a solid is able to take up moisture from the air, it is described as hygroscopic. A small number of anhydrous solids that have low vapor pressures not only take up atmospheric moisture on even the driest of days, but will become wet as water molecules are adsorbed onto their surfaces this is most commonly observed with sodium hydroxide and calcium chloride. With these solids, the concentrated solution that results continues to draw in water from the air so that the entire crystal eventually dissolves into a puddle of its own making solids exhibiting this behavior are said to be deliquescent. 

Clear white to yellow-pink deliquescent crystals with an odor like rotten eggs due to formation of hydrogen sulfide. Commercial material may be yellow or brick-red lumps or flakes. It is unstable and discolors upon exposure to air. It undergoes autoxidation to form polysulfur, thiosulfate, and sulfate. It absorbs carbon dioxide from the air to form sodium carbonate. Moist sodium sulfide is spontaneously flammable upon drying in air. This material is hazardous through ingestion and produces local skin/eye impacts. 

Atmospheric aerosols are hygroscopic, taking up and releasing water as the RH changes (see also Section C.l) because some of the chemical components are themselves deliquescent in pure form. For example, sodium chloride, the major component of sea salt, deliquesces at 298 K at an RH of 75%, whereas ammonium sulfate, (NH4)2S04, and ammonium nitrate, NH4N03, deliquesce at 80 and 62% RH, respectively. (See Table 9.16 for the deliquescence points of some common constituents of atmospheric particles.) De-... 

The slightly deliquescent sodium (1-hydrate) and anhydrous potassium salts are readily obtained by metathesis of the barium salt in hot water with the requisite amounts of sodium or potassium sulfate, removal of the barium sulfate that forms, and evaporation of the filtrate. 

Five grams of copper sulfate 5-hydrate are dissolved in 20ml of water and 3.5g of dipropylenetriamine are added with stirring. Acetone is added to the blue liquid until the product has been completely precipitated as an oil the supernatant liquid should be almost colorless. The oil is repeatedly triturated with small portions of acetone in a mortar until it forms a solid it is brought onto the filter with the same solvent and washed with a little ether. While the deep blue product is still moist, it is rapidly transferred to a vacuum desiccator and pumped dry. The material is extremely deliquescent. Losses in the preparation are only mechanical. The complex sulfate gives no precipitate with solutions of iodide, dithionate, ferricyanide, or persulfate ions. In concentrated aqueous medium, however, the addition of solid sodium fluoroborate causes partial precipitation of the relatively insoluble complex fluoroborate. 

Sodium Nitrate—Cubic or Chili saltpetre—-Sodii nitras (TJ. S.) —Sodee nitras (Br.)—NaNO,—85—occurs in natural deposits in Chili and Peru. It crystallizes in anhydrous, deliquescent rhom-bohedra cooling and somewhat bitter in taste fuses at 310° (590° F.) very soluble in HaO. Heated with HaSOi, it is decomposed, yielding HNOa and hydrosodic sulfate HaS04- -NaNOa —HNaS04+HNOa. This reaction is that used for obtaining h no3. 

---