Acid-decomposable glasses

Mercuric Sulfate. Mercuric s Af2iX.e.[7783-35-9] HgSO, is a colorless compound soluble ia acidic solutions, but decomposed by water to form the yellow water-iasoluble basic sulfate, HgSO 2HgO. Mercuric sulfate is prepared by reaction of a freshly prepared and washed wet filter cake of yellow mercuric oxide with sulfuric acid ia glass or glass-lined vessels. The product is used as a catalyst and with sodium chloride as an extractant of gold and silver from roasted pyrites. 

G. S. Serullas treated potassium chlorate with an excess of hydrofluosilicic acid the clear liquid was decanted from the sparingly soluble potassium fluosilicate, the soln. evaporated below 30°, and filtered through glass powder J. J. Berzelius evaporated the acid liquid mixed with finely divided silica below 30° in air, or over cone, sulphuric acid and potassium hydroxide in vacuo. The excess of hydrofluoric acid was volatilized as silicon fluoride, and the clear liquid was then filtered from the excess of silica. R. Bottger treated sodium chlorate with oxalic acid whereby sparingly soluble sodium oxalate was formed J. L. Wheeler, and T. B. Munroe treated sodium chlorate with hydrofluosilicic acid and M. Brandau treated potassium chlorate with aluminium sulphate and sulphuric acid and precipitated the alum so formed with alcohol. Chloric acid is formed in many reactions with hypochlorous and chlorous acid for example, it is formed when an aq. soln. of chlorine or hypochlorous or chlorous acid decomposes in light. It is also formed when an aq. soln. of chlorine dioxide stands in darkness or in light. A mixture of alkali chlorate and chlorite is formed when an aq. soln. of an alkali hydroxide is treated with chlorine dioxide. 

Action, of Acids.—The acids, in their turn, should act on glasses with facility. Among these, the hydrofluoric acid must be classed by itself, its action being quite peculiar. The other acids tend to decompose glass, by seizing on the bases and setting tho silica free. 

Exceptional effects on silicate glasses are exhibited by acids HF and H3P04 which decompose glass as a whole, similarly to alkaline solutions. 

Properties Red, crystadine solid. D 3.54. Decomposed by water and by heat. Soluble in acids. Attacks glass when hot. 

With metallic oxides, hydrofluoric acid gives rise to water and metallic fluorides HF - - MO = HO -F MF. The afiinity of fluorine for silicon is such, that hydrofluoric acid decomposes all silicious compounds and this explains its corrosive action on glass and porcelain. Berzelius has employed this acid as a means of analysing silicious minerals. As the fluoride of silicium is gaseous, any such mineral, if digested with hydrofluoric acid, soon loses all its silica, and is dissolved, so that the other ingredients may be determined. 

Zr(OH), a toxic, amorphous white powder insoluble in water, soluble in dilute mineral acids decomposes at 550°C used in pigments, glass, and dyes, and to make zirconium compounds. 

J. B. Senderens said that the chromate is not altered when boiled for a week with water and sulphur. The presence of free sulphur, or sulphides, gradually darkens chrome-yellow owing to the formation of lead sulphide. E. F. Anthon heated in a glass tube a mixture of lead chromate with one-eighth of its weight of sulphur, and found that the product takes fire with incandescence on exposure to air, forming sulphur dioxide, and chromic and lead oxides. H. Moissan and P. Lebeau said that sulphur hexafluoride is not decomposed by molten lead chromate. Hot sulphuric acid decomposes lead chromate, forming lead sulphate, and H. Schwarz found that for complete decomposition an excess of 4 to 5 mols of sulphuric acid is necessary ... 

Peifluoroalkanecarboxylic acids can be heated to 400°C in borosilicate glass without significant decomposition [7]. At higher temperatures (550 C), perfluoroalkanecarboxylic acids decompose, yielding an olefin, HF, and CO2 [8] (Table 3.4). 

Dihydroxyacetophenone. Finely powder a mixture of 40 g. of dry hydroquinone diacetate (1) and 87 g. of anhydrous aluminium chloride in a glass mortar and introduce it into a 500 ml. round-bottomed flask, fitted with an air condenser protected by a calcium chloride tube and connected to a gas absorption trap (Fig. II, 8, 1). Immerse the flask in an oil bath and heat slowly so that the temperature reaches 110-120° at the end of about 30 minutes the evolution of hydrogen chloride then hegins. Raise the temperature slowly to 160-165° and maintain this temperature for 3 hours. Remove the flask from the oil bath and allow to cool. Add 280 g. of crushed ice followed by 20 ml. of concentrated hydrochloric acid in order to decompose the excess of aluminium chloride. Filter the resulting solid with suction and wash it with two 80 ml. portions of cold water. Recrystallise the crude product from 200 ml. of 95 per cent, ethanol. The 3 ield of pure 2 5-dihydroxyacetophenone, m.p. 202-203°, is 23 g. 

To decompose the acetone semicarbazone, warm 58 g. with 50 ml. of concentrated hydrochloric acid until it just dissolves. Cool in ice the semicarbazide hydrochloride separates as a thick crystaUine mass. Filter at the pump through a sintered glass funnel, and wash with a small quantity of alcohol and then with ether dry in the air. The yield of pure semicarbazide hydrochloride, m.p. 173° (decomp.), is 35 g. A further quantity of product may be obtained either by saturating the mother liquor with hydrogen chloride or by treating it with twice its volume of alcohol and then with ether. 

The salts rapidly hydroly2e to form NF and O2, and react with glass at temperatures above 85°C to form NF and SiF (21). The NF" 4 salts are stable in dry atmospheres to 200°C, but rapidly decompose above 300°C to yield NF, F2, and the corresponding Lewis acid. Therefore, these salts are solid sources of NF and F2, free of atmospheric contaminants and HF. 

Acids and alkaUes were used to decompose the fiber to cellulose. The alkaU digester process, developed in 1899, is stiU used. Fiber glass reinforcement must be removed mechanically before the mbber can be reclaimed. A highly efficient method involves hammer mills and reel beaters to separate the fiber from the mbber an air current subsequentiy drives off the fiber. 

Stannous Oxide. Stannous oxide, SnO ((tin(II) oxide), mol wt 134.70, sp gr 6.5) is a stable, blue-black, crystalline product that decomposes at above 385°C. It is insoluble in water or methanol, but is readily soluble in acids and concentrated alkaHes. It is generally prepared from the precipitation of a stannous oxide hydrate from a solution of stannous chloride with alkaH. Treatment at controUed pH in water near the boiling point converts the hydrate to the oxide. Stannous oxide reacts readily with organic acids and mineral acids, which accounts and for its primary use as an intermediate in the manufacture of other tin compounds. Minor uses of stannous oxide are in the preparation of gold—tin and copper—tin mby glass. 

Alternatively dissolve the salt (30g) in glacial acetic acid (200mL) by heating and filter. If crystals do not appear, the glass container should be rubbed with a glass rod to induce crystn which occurs within Ih. If not, allow to stand for a few days. Filter the cinnamon brown crystals which have a sliky lustre and dry over CaO. Keep away from moisture as it is decomposed by cold H2O. [Lux in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Vol II, p 1469 1963 Williams and Hunter Can J Chem 54 3830 1976.]... 

Neutralization to phenolphthalein is satisfactory, but a glass electrode might give better results. Hydroxyurea is decomposed very rapidly in aqueous acidic medium, whereas its metallic salts (sodium or the copper complex salts) are stable. 

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