Alkali carbonates and hydroxides

Tungsten trisulfide [12125-19-8], WS3, is a chocolate-brown powder, slighdy soluble in cold water, but readily forming a colloidal solution in hot water. It is prepared by treating an alkah-metal thiotungstate with HC1 (52). Tungsten trisulfide is soluble in alkali carbonates and hydroxides. 

BORACIC ACID (10043-35-3) Aqueous solution is a weak acid incompatible with alkali carbonates and hydroxides. Incompatible potassium. Contact with acetic anhydride forms a heat-sensitive explosive. 

Hydrochloride, C,H ClN02, crystals, mp 172-175°. Slightly bitter taste followed by numbness of the mouth. Stable in air. One gram dissolves in l ml water. Sol in ale, chloroform. Insol in ether, olive oil. A I I0 aq soln is faintly add to litmus. Alkali carbonates and hydroxides predpi-tate piperocaine base as an oil from aq sol ns of the hydrochloride. LDm in rats 1.3 g/kg s.c. 20 mg/kg i.v. therap cat Local anesthetic. therap Cat (vet) Local anesthetic. 

For results upon mixtures of calcium hydroxide and alkali carbonates and hydroxides, see Bodlander — Z. angew. Chem. 18, 1138, 05. 

It must be emphasized that boron nitride has an exceptionally good resistance to most molten salts and glasses, probably due to its resistance to wetting. It is inert to a number of corrosive molten salts, such as alkali halides, lithium borate and cryolites, and has a good resistance to molten glasses. However, it does react with molten alkali carbonates and hydroxides. 

The first evidence of a gas being a distinct chemical entity and not merely a modification of atmospheric air was provided by Joseph Black (1728-1799). The origin of Black s work was an attempt to find a gentle but effective alkaline solvent for urinary calculi (stones), and in the course of his research Black unravelled the relationship between mild and caustic alkalis (carbonates and hydroxides). Black s paper. Experiments on Magnesia Alba, Quick-lime and other alcaline substances, was published in 1756. 

Adsorption of NOx on y-alumina, as well as that alkalized with alkali carbonates and hydroxides, has been studied by Lee et al. (1998 1999). It is known that NO does not adsorb effectively on activated alumina, whereas only NO2 adsorbs strongly. The mechanism of adsorption of NO2 on alumina, was studied by Nelli and Rochelle (1996). Their study suggested that the adsorption on alumina (and other oxide sorbents) follows the general mechanism ... 

Tantalum Oxides. Tantalum pentoxide [1314-61 -0] Ta20, (mp = 1880°C, density = 8.73 g/cm ) is a white powder existing in two thermodynamically stable modifications. The orthorombic P-phase changes at 1360°C into the tetragonal a-modiftcation. The existence of an S-modiftcation has also been reported (70). Tantalum pentoxide reacts slowly with hot hydrofluoric acid but is insoluble in water and in most solutions of acids and alkalies. For analytical purposes, it can be dissolved by fusion with alkali hydroxides, alkali carbonates, and potassium pyrosulfate. 

Lithium was recognized as a new alkali metal by J. A. Arfved.son in 1817 whilst he was working as a young assistant in J. J. Berzelius s laboratory. He noted that Li compounds were similar to those of Na and K but that the carbonate and hydroxide were much less soluble... 

Discussion. The hydroxides of sodium, potassium, and barium are generally employed for the preparation of solutions of standard alkalis they are water-soluble strong bases. Solutions made from aqueous ammonia are undesirable, because they tend to lose ammonia, especially if the concentration exceeds 0.5M moreover, it is a weak base, and difficulties arise in titrations with weak acids (compare Section 10.15). Sodium hydroxide is most commonly used because of its cheapness. None of these solid hydroxides can be obtained pure, so that a standard solution cannot be prepared by dissolving a known weight in a definite volume of water. Both sodium hydroxide and potassium hydroxide are extremely hygroscopic a certain amount of alkali carbonate and water are always present. Exact results cannot be obtained in the presence of carbonate with some indicators, and it is therefore necessary to discuss methods for the preparation of carbonate-free alkali solutions. For many purposes sodium hydroxide (which contains 1-2 per cent of sodium carbonate) is sufficiently pure. 

Admixture incompatibilities - Magnesium sulfate in solution may result in a precipitate formation when mixed with solutions containing Alcohol (in high concentrations) alkali carbonates and bicarbonates alkali hydroxides arsenates barium calcium clindamycin phosphate heavy metals hydrocortisone sodium succinate phosphates polymyxin B sulfate procaine hydrochloride salicylates strontium tartrates. 

Sulfur combines direcdy with hydrogen at 150—200°C to form hydrogen sulfide. Molten sulfur reacts with hydrogen to form hydrogen polysulfides. At red heat, sulfur and carbon unite to form carbon disulfide. This is a commercially important reaction in Europe, although natural gas is used to produce carbon disulfide in the United States. In aqueous solutions of alkali carbonates and alkali and alkaline-earth hydroxides, sulfur reacts to form sulfides, polysulfides, thiosulfates, and sulfites. 

Sulphur is soluble in solutions of the sulphides of the alkali metals, including ammonium, with the formation of yellow solutions of polysulphides.6 The alkali carbonates and the hydroxides of the alkali and alkaline earth metals, in aqueous solution, also dissolve sulphur, producing sulphides or polysulphidcs together with thiosulphates and sulphites. In all probability the ideal equation for hydroxides is ... 

Hydroxylamine-disulphonic Acid, N(0H)(S03H)2.—The alkali hydroxylamine-disulphonates may be prepared by the addition of the alkali hydrogen sulphite in concentrated aqueous solution to the alkali nitrite. They are also formed when excess of sulphur dioxide is passed through a solution containing the alkali nitrite and either the alkali carbonate or hydroxide. The presence of caustic alkali confers stability on the compound, whilst acids decompose it even in the cold, hydroxyl-amine monosulphonie acid being formed.6... 

The metaniobates of the alkali metals, MNb03, the orthoniobates MjNbOj and the pyroniobates, M+NbeOy, where M is an alkali metal, can be prepared by various alkali carbonate or hydroxide fusion processes. Niobium fonns a nitride, NbN, and a carbide, NbC. 

Thorium has the oxidation state of (IV) in all of its important compounds. Its oxide, ThCL. and its hydroxide are entirely basic. The nature of the 10ns present in a number of solutions of the soluble compounds is not known with certainty. Complex ions involving sulfate are suggested by the increased solubility of the sulfate in solutions of the acid sulfates. Similarly, other complex ions are suggested by the solubility of the carbonate in excess alkali carbonate and of the oxalate in ammonium oxalate. Such ready complex ion formation is consistent with the high positive charge of the thorium-flV) ion. 

High alkalinity is due to the presence of bicarbonates, carbonates and hydroxides of the alkaline earth and alkali metals, principally calcium, magnesium, sodium and potassium. The effect of high alkalinity is to buffer acidity in a soft drink, resulting in the creation of a bland taste, ft is essential therefore to maintain a consistent alkalinity level. The majority of manufacturers aim for below 50 mg/1 as CaC03. Alkalinity may be reduced by coagulation treatment or by ion exchange. 

Potassium and sodium hydroxide are far more energetic than the alkali carbonates and are used only when a powerful, fast-acting developer is required. Developers compounded with caustic alkalis have poor keeping properties and are soon exhausted. 

Ditungsten trisilicide [12138-30-6], W2Sig, gray in color and having an sp gr of 10.9, is insoluble in water, acid, or alkaline solutions. It is readily attacked by HN03—HF and fused alkali-metal carbonates and hydroxides. 

Permanent hardness can also be estimated by the alkalimetric method of Wartha and Pfeifer. A measured volume (200 e.e.) of the water is boiled with 50 c.e. of a mixture of decmormal solutions of sodium carbonate and hydroxide in equal amounts after restoring to the original volume and allowing the solution to settle, the residual alkali is determined by titration with standard acid. As the bicarbonates do not cause any consumption of alkali, there is a direct proportionality between the quantity of alkali which disappears and the total amount of sulphates and chlorides of calcium and magnesium. Sodium carbonate alone does not efficiently precipitate magnesium salts from solution, but precipitation as the hydroxide is complete if excess of sodium hydroxide is present it is for this reasoii that a mixture of sodium carbonate and hydroxide is applied 3 (see also p. 211). 

In the series of the alkali metal carbonates and -hydroxides the cesimn compounds are the strongest bases [14]. For reasons of simpler handling the less hygroscopic carbonate is often preferred to the hydroxide. In dipolar aprotic solvents, carboxylic acids [15], phenols [16], thiols [17, 18] and sulfonamides [19] are easily deprotonated by cesium carbonate, whereas with carbamates such as e.g. benzyloxycarbonyl- ( Z -)protected amino acids no reaction occurs [20]. 

The readiness with which chromium chromate is converted by ammonia, alkali carbonate, or hydroxide, or by boiling water, into chromium hydroxide and chromate is considered to be evidence of its salt-like constitution. 

Si02/metal oxide > 1.5 from quartz sand and alkali carbonates or hydroxides... 

---