Blue flames

Carbon monoxide burns with a characteristic blue flame in air or oxygen. The reaction... 

At high temperatures oxygen reacts with the nitrogen in the air forming small amounts of nitrogen oxide (p. 210). Sulphur burns with a blue flame when heated in air to form sulphur dioxide SO2, and a little sulphur trioxide SO3. Selenium and tellurium also burn with a blue flame when heated in air, but form only their dioxides, Se02 and Te02. 

Hydrogen sulphide bums in air with a blue flame yielding sulphur dioxide, but if the air supply is limited, preferential combustion to form sulphur occurs ... 

Carbon monoxide test. Warm together carefully 0 5 ml. of formic acid (or 0 5 g. of a formate) and i ml. of cone. 112804. Identify the carbon monoxide by igniting the gas evolved and observing the pale blue flame travel down the test-tube. Note that dilute solutions of formic acid will not give this test. HCOOH — HjO — CO. 

Sulphuric add test. To 0-5 g. of oxalic acid or of an oxalate, add I ml. of cone. H2SO4 and warm CO and COg are evolved (cf. formic acid). The CO burns with a blue flame. Detect the COg by passing the mixed gases evolved into lime-water. It is essential to test for the COj in a separate reaction, or (if the same test-tube is used) before testing for CO. 

Its conductivity increases slightly with exposure to light. It can be doped with silver, copper, gold, tin, or other elements. In air, tellurium burns with a greenish-blue flames, forming the dioxide. Molten tellurium corrodes iron, copper, and stainless steel. 

When ignited, nonfilled acetal resins bum in air with a characteristic dull blue flame. 

Whereas there is no universally accepted specification for marketed natural gas, standards addressed in the United States are Hsted in Table 6 (8). In addition to these specifications, the combustion behavior of natural gases is frequently characteri2ed by several parameters that aid in assessing the influence of compositional variations on the performance of a gas burner or burner configuration. The parameters of flash-back and blow-off limits help to define the operational limits of a burner with respect to flow rates. The yeUow-tip index helps to define the conditions under which components of the natural gas do not undergo complete combustion, and the characteristic blue flame of natural gas burners begins to show yellow at the flame tip. These... 

Cool Flames. An intriguing phenomenon known as "cool" flames or oscillations appears to be intimately associated with NTC relationships. A cool flame occurs in static systems at certain compositions of hydrocarbon and oxygen mixtures over certain ranges of temperature and pressure. After an induction period of a few minutes, a pale blue flame may propagate slowly outward from the center of the reaction vessel. Depending on conditions, several such flames may be seen in succession. As many as five have been reported for propane (75) and for methyl ethyl ketone (76) six have been reported for butane (77). As many as 10 cool flames have been reported for some alkanes (60). The relationships of cool flames to other VPO domains are depicted in Figure 6. 

Chemica.1 Properties. Reviews of carbonyl sulfide chemistry are available (18,23,24). Carbonyl sulfide is a stable compound and can be stored under pressure ia steel cylinders as compressed gas ia equiUbrium with Hquid. At ca 600°C carbonyl sulfide disproportionates to carbon dioxide and carbon disulfide at ca 900°C it dissociates to carbon monoxide and sulfur. It bums with a blue flame to carbon dioxide and sulfur dioxide. Carbonyl sulfide reacts... 

Aqueous solutions have low conductivities resulting from extensive complex ion formation. The haUdes, along with the chalcogenides, are sometimes used in pyrotechnics to give blue flames and as catalysts for a number of organic reactions. 

Hydrogen sulphide is used in the preparation of metal sulphides, oil additives ete., in the purifieation and separation of metals, as an analytieal reagent and as raw material in organie synthesis. It burns in air with a blue flame ... 

The substitution of one hydroxyl radical for a hydrogen atom in propane produces propyl alcohol, or propanol, which has several uses. Its molecular formula is C3H7OH. Propyl alcohol has a flash point of 77°F and, like all the alcohols, bums with a pale blue flame. More commonly known is the isomer of propyl alcohol, isopropyl alcohol. Since it is an isomer, it has the same molecular formula as propyl alcohol but a different structural formula. Isopropyl alcohol has a flash point of 53 F. Its ignition temperamre is 850°F, while propyl alcohol s ignition temperature is 700 F, another effect of the different stmcture. Isopropyl alcohol, or 2-propanol (its proper name) is used in the manufacture of many different chemicals, but is best known as rubbing alcohol. 

Alkaline hydrolysis yields predominantly thiosulfate. SSF2 bums with a pale-blue flame when ignited, to yield SO2, SOF2 and SO2F2. 

Vaporizing 10-40 kW No Kerosene, gas oil <5 On/off Normally blue flame Central heating... 

FIGURE C.1 Elemental sulfur burns in air with a blue flame and produces the dense gas sulfur dioxide, a compound of sulfur and oxygen. 

In the absence of gravity, the properties of a candle flame change dramatically [36,39,41]. Figure 8.1.3 shows a candle flame on the Mir space station, in which the melt layer was hemispherical and much thicker than that in normal gravity, and the flame was smaller, spherical, and less sooty, uncovering the blue flame zone. There was significant circulation in the liquid phase (as a result of surface-tension-driven flow caused... 

Although many reactions and uses of sulfur will be described, about 85% of the sulfur produced is used in making sulfuric acid, and about two-thirds of the acid is used in the production of fertilizer (see Chapter 14). Sulfur is rather reactive, so it reacts with most other elements. It produces a blue flame when it bums in air,... 

The yellow flame of traditional oil burners is often surveyed by flame guards that react on the visible emission. More modern oil heaters use blue-burning flames. There, the carbon black of the combustion process is redirected to the combustion area for a more complete combustion, thus giving higher efficiency. With the reduced carbon black their yellow emission in the visible also vanishes, leaving an almost invisible flame, see Fig. 5.44. For these blue flames surveillance based on UV emission is preferable... 

Solution At extinction we expect the flame to be small so we will assume no flame radiative heat flux and Xr = 0. This is not a bad approximation since near extinction soot is reduced and a blue flame is common. For PMMA, Ij., = 1- Substituting values into Equation (9.79), we obtain (approximating Lm L)... 

Cyclic gas generators converted coke, a by-product of high-temperature pyrolysis process, to a synthetic gas by alternatively exposing the coke to air to provide heat and to steam to produce a gas that burned with a blue flame. The coal gas was know as blue water gas (Probstein, R. F. and Hicks, R. E., Synthetic Fuels, McGraw-Hill, 1982, p. 7). 

Hot Flame Ignition - A rapid self-sustaining, sometimes audible gas phase reaction of the sample or its decomposition products with an oxidant. A readily visible yellow or blue flame usually accompanies the reaction. 

If you have melting point tubes that are open at both ends and you try to take a melting point with one, it should come as no surprise when your compound falls out of the tube. You ll have to close off one end, to keep your sample from falling out (Fig. 32). So light a burner and get a stiff small blue flame. SLOWLY touch the end of the tube to the side of the flame, and hold it there. You should get a yellow sodium flame, and the tube will close up. There is no need to rotate the tube. And remember, touch— just touch—the edge of the flame, and hold the tube there. Don t feel you have to push the tube way into the flame. 

You ll get a wavy yellow flame, something you don t really want. But at least it ll light. Now open the air collar a little. The yellow disappears a blue flame forms. This is what you want. 

Now, adjust the needle valve and collar (the adjustments play off each other) for a steady blue flame. 

On the wall directly opposite you, in place of a tapestry, hangs a curtain of cloth-of-gold. Above the curtain, but beneath the window, hangs a chivalric shield. The shield s field is white and its heraldic device is a gold phoenix, issuant from a nest of azure-blue flames. This is the east wall of the hall. Your personal siege is placed on the western arc of the Round Table. 

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