Sodium nitrate melting point

Salt baths that are used for certain thermal treatments of aluminium alloys such as homogenisation and solution heat treatment are mixtures of sodium nitrate (melting point, 307 °C) and potassium nitrate (melting point, 334 °C)." The mass loss of aluminium in a nitrate bath is 20 mg-m -h of immersion, which corresponds to a decrease in thickness of less than 0.01 p,m h. This is very acceptable for thermal treatments that do not exceed a few hours. 

To a stirred and refluxing solution of 40 parts of benzene and 35 parts of dimethylformamide (both solvents previously dried azeotropically) are added successively 1.6 parts of sodium hydride and 7.7 parts of Ct-(2,4-dichlorophenyl)imidazole-1-ethanol, (coolingon ice is necessary). After the addition is complete, stirring and refluxing is continued for 30 minutes. Then there are added 7.8 parts of 2,6-dichlorobenzyl chloride and the whole is stirred at reflux for another 3 hours. The reaction mixture is poured onto water and the product 1-[2,4-dichloro-/3 (2,6-dichlorobenzyloxy)phenethyl] imidazole, is extracted with benzene. The extract is washed twice with water, dried, filtered and evaporated in vacuo. The bese residue is dissolved in a mixture of acetone and diisopropyl ether and to this solution is added an excess of concentrated nitric acid solution. The precipitated nitrate salt is filtered off and recrystallized from a mixture of methanol and diisopropyl ether, yielding 1-[2,4-dichloro- (2,6-dichlorobenzyl-oxv)phenethyl] imidazole nitrate melting point 179°C. 

Primary aromatic amides are crystaUine sohds with definite melting points. Upon boiling with 10-20 per cent, sodium or potassium hydroxide solution, they are hydrolysed with the evolution of ammonia (vapour turns red htmus paper blue and mercurous nitrate paper black) and the formation of the alkah metal salt of the acid ... 

Amino-l,2,4-triazole has been prepared by evaporating formylguanidine nitrate with sodium carbonate, and from 5(3)-amino-1,2,4-triazole carboxjdic acid-3(S) by heating above its melting point, or by a long digestion with acetic acid. ... 

The experiment may also be repeated using a platinum (indicator) electrode and a tungsten wire reference electrode. If the tungsten electrode has been left idle for more than a few days, the surface must be cleaned by dipping into just molten sodium nitrate (CARE ). The salt should be only just at the melting point or the tungsten will be rapidly attacked it should remain in the melt for a few seconds only and is then thoroughly washed with distilled water. 

The crude product contains isomers other than that required and also nitrated phenolic compounds resulting from side reactions. The usual method of purification is to treat the crude product with sodium sulphite, which converts asymmetric trinitro compounds to sulphonic acid derivatives, and to wash out the resulting soluble products with alkaline water. The purity of the product is determined by the melting point, the minimum value for Grade I TNT commonly being 80-2°C. Unless adequate purity is achieved, slow exudation of impurities can occur during storage and the TNT then becomes insensitive. 

For purification the crude product is boiled with glacial acetic acid (preferably in the extraction apparatus shown in Fig. 27). Fine red needles melting point 289°. Sublimation in a vacuum from a sausage flask is also to be recommended the sausage should be fixed low down and the bulb completely immersed in a nitrate bath (equal parts of potassium and sodium nitrates). Much poorer yields of alizarin are obtained by using an open round-bottomed flask at 189°-190°. 

Other oxidizers, including barium chromate (BaCrO,), lead chromate (PbCrO 4), sodium nitrate (NaNO 3), lead dioxide (PbO 2), and barium peroxide (BaO 2) will also be encountered in subsequent chapters. Bear in mind that reactivity and ease of ignition are often related to the melting point of the oxidizer, and the volatility of the reaction products determines the amount of gas that will be formed from a given oxidizer /fuel combination. Table 3.2 contains the physical and chemical properties of the common oxidizers, and Table 5.8 lists the melting and boiling points of some of the common reaction products. 

Crude TNT contains isomers and nitrated phenolic compounds resulting from side reactions. The usual method of purification is to treat crude TNT with 4% sodium sulfite solution at pH 8-9, which converts the unsymmetrical trinitro compounds to sulfonic acid derivatives. These by-products are then removed by washing with an alkaline solution. Pure TNT is then washed with hot water, flaked and packed. It is important to remove the waste acid and unsymmetrical trinitrotoluenes together with any by-products of nitration as they will degrade the TNT, reduce its shelf life, increase its sensitivity and reduce its compatibility with metals and other materials. Trace amounts of unsymmetrical trinitrotoluenes and by-products will also lower the melting point of TNT. TNT can be further recrystallized from organic solvents or 62% nitric acid. 

A fused salt bath consisting of 8.5 parts (by weight) of sodium nitrite and 10 parts of potassium nitrate has a melting point of about 140° and may replace the metal bath. 

When dealing with precipitated salts it is important to know the physical state in which the salt is present inside the reactor, either solid or liquid. For example, sodium nitrate has melting point 306.8 °C, lower than the operating temperature. Therefore, once saturating conditions are surpassed, sodium nitrate does not adhere to the reactor walls as a solid but drains itself downwards. Since it is denser than supercritical water [27], care should be taken to prevent its accumulation at the bottom of the reactor. 

Any characteristic that can be used to describe or identify matter is called a property. Examples include size, amount, odor, color, and temperature. Still other properties include such characteristics as melting point, solubility, and chemical behavior. For example, we might list some properties of sodium chloride (table salt) by saying that it melts at 1474°F (or 801°C), dissolves in water, and undergoes a chemical reaction when it comes into contact with a silver nitrate solution. 

A solution of sodium nitrate (0.69 g, 10 mmol) in water (5 ml) was added at 0-5°C to a solution of 6-amino-2,3-dimethoxy-l,4-naphthoquinone (1.17 g, 5 mmol) in 5 1 acetic acid water (25 ml) containing concentrated hydrochloric acid (1.7 ml). A further quantity of sodium nitrite (0.69 g) was then added to the reaction mixture after cooling to -5°C, followed by a solution of cuprous chloride (0.6 g) in concentrated hydrochloric acid (5 ml). The mixture was allowed to warm to room temperature and solid cuprous chloride was added portionwise until the mixture assumed a green color. Water was then added to the reaction mixture and the precipitated yellow solid filtered off, washed with water and recrystallized from methanol water (2 1) giving 1.01 g of 6-chloro-2,3-dimethoxy-l,4-naphthoquinone, melting point 93-94°C (from ether-petrolium ether). 

Ferrous nitrate hexahydrate (60 mg) followed by sodium (4.5 g, 0.196 g-atom) were added to liquid ammonia. To this mixture was added a solution of 3-methylpyridine (10.0 g, 0.093 mole) in N,N-dimethylaniline (21 ml) over a period of 5 min. The ammonia was allowed to evaporate and the residue heated under nitrogen by means of an oil bath maintained at 180°C for 18 h. The cooled residue was treated with ice (50 g) followed by 2 N sodium hydroxide (50 ml). The mixture was triturated for 2 h and then filtered. The collected solid was washed with boiling toluene (2 times 100 ml). The toluene layer was separated from the combined filtrate and washings, concentrated to about 50 ml and extracted with 5% aqueous acetic acid (5 times 20 ml). The combined extracts were filtered and reduced to dryness. The residue was recrystallized from methylcyclohexane to give 2-amino-3-methylpyridine acetate (4.9 g, 29%), melting point 85°-95°C. The acetate (2.5 g, 1.37 mmoles) was briefly suspended in 1 N sodium hydroxide (50 ml). The mixture was extracted with methylene chloride. The extract was washed with water, dried, and concentrated to give 2-amino-3-methylpyridine as an oil. 

Styphnic acid is a yellow crystalline solid with a melting point of 176 Celsius. It is insoluble in water, but soluble in alcohol, ether, and acetic acid. Styphnic acid turns deep yellow on contact with air, so it should be stored in tightly sealed bottles in a cool place. The compound is corrosive and readily forms salts with metal hydroxides and carbonates—many of which are primary explosives, i.e., lead styphnate. Styphnic acid bums rapidly and violently when ignited. For safety reasons, styphnic acid should be stored wet with 10% water. It is used primarily in the manufacture of lead styphnate, but is used with outstanding results in explosives compositions when mixed with nitrocellulose, sodium nitrate, or ammonium perchlorate and... 

---