Steam on iron

After describing the experiments made with Meusnier (see p. 447) on the action of steam on iron and on charcoal, Lavoisier said later that in January-February 1785 the composition of water (85 oxygen and 15 hydrogen) was demonstrated in the presence of the Commissaires de I Academie , and nous rendrons compte a I Academie, dans un tr -grand detail, des r ultats que nous avons obtenus . This was never done. 

Cobalt is appreciably less reactive than iron, and so contrasts less markedly with the two heavier members of its triad. It is stable to atmospheric oxygen unless heated, when it is oxidized first to C03O4 above 900°C the product is CoO which is also produced by the action of steam on the red-hot metal. It dissolves rather slowly in dil mineral acids giving salts of Co and reacts on heating with the halogens and other non-metals such as B, C, P, As and S, but is unreactive to H2 and N2. 

Trip valve Shuts off steam on overspeed Steel, stainless, and nickel iron... 

Another common illustration to which the same considerations apply is that of reaction of steam on red hot iron. This reaction is represented by... 

We often generate steam when ironing clothes made of cotton. The steam forms even if the cloth previously felt dry. But the steam is only formed if the shirt was dried outside, e.g. on a clothes line. We see no steam if the shirt was dried on a radiator before ironing. 

A shirt dried previously on a radiator does not form steam while ironing because the heat from the radiator was itself sufficient to break the adsorptive bonds between the water and the cotton. Any adsorbed water was lost before the process of ironing commenced. 

Ammonium chloride is also formed by the action of hydrochloric acid on a soln. of ammonia or ammonium carbonate J. G. Qentele 5 made it by the double decomposition of ammonium bicarbonate and sodium, magnesium, calcium, and other chlorides H. J. E. Hennebutte and E. Mesnard, and A. Dubose and M. Heuzey, made it by the action of ammonium bicarbonate or sulphate on the double chloride of iron and calcium and it is made by the action of soln. of ammonium sulphate and sodium chloride when the soln. is cone, the crystals of sodium sulphate separate out and they are removed by suitable shovels the cone. soln. of ammonium chloride which remains is purified by crystallization. Ammonium chloride can also be obtained by sublimation from a dry intimate mixture of the same two salts. A. French made it by the joint action of air and steam on a mixture of salt, pyrites, and carbon or organic matter 2NaCl+4H20-j-S02+C-j-N2=2NH4Cl-i-Na2S04-i-C02. 

If the material is not decomposed by heat it can be dried much more rapidly in a warm place, as on a steam-heated iron plate (steam table) but a product containing water of crystallization should never he dried at an elevated temperature. During the drying the preparation must, of course, be carefully protected from dust. 

Already familiar is the convenient laboratory preparation of elementary hydrogen by reduction of acids. Generally those metals lying between magnesium and tin in oxidation potential are appropriate. Less convenient but more spectacular is the production of hydrogen from action of the alkali metals on water. For small quantities of hydrogen, reaction of metal hydrides with water has been used such hydrides will be considered later in the chapter. Commercial preparations of H2 by reduction of steam with iron or coke and, finally, by the electrolysis of water should be recalled. 

Reduction of Metallic Oxides.—Hydrogen can displace many metals from their oxides, the reduction taking place at the ordinary temperature, as with silver and palladium oxides, or on heating, as with the oxides of copper, cadmium, lead, antimony, nickel, cobalt, and iron. Sometimes these reductions are incomplete, an equilibrium being attained. Such equilibria depend on the experimental conditions, an example being the action of steam on heated iron (p. 15). 

Metal granules also have been found in cokes formed or deposited on iron, cobalt, and nickel foils in experiments using methane, propane, propylene, and butadiene (7-10). Platelet-type coke, whose properties match those of graphite also was produced in some cases. Lahaye et al. (11) investigated the steam cracking of cyclohexane, toluene, and n-hexane over quartz, electrode graphite, and refractory steel. They report that heavy hydrocarbon species form in the gas phase, condense into liquid droplets which then strike the solid surface, and finally react on the solid surfaces to produce carbonaceous products. The liquid droplets wet and spread out on certain surfaces better than on others. 

Iron is an active metal, which displaces hydrogen easily from dilute acids. It burns in oxygen to produce ferrous-ferric oxide, FcgO. This oxide is also made by interaction with superheated steam. One metnod of preventing rusting involves the production of an adherent surface layer of this oxide on iron. 

Derivation (1) Action of air, steam, or carbon dioxide on iron (2) specially pure grade by precipitating hydrated ferric oxide from a solution of iron salts, dehydrating, and reducing with hydrogen, (3) occurs in nature as the mineral magnetite. 

Thermodynamic data on the iron oxides are not directly available but calculations based on free energy values determined from equilibrium data between steam and iron and from specific heat data at low temperatures by the entropy principle91 show that the formation of methanol by the reactions shown is very unfavorable. 

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