Reaction with oxygen gas

Whereas the production of iron is basically a reduction process (converting iron oxides to metallic iron), the conversion of iron to steel is essentially an oxidation process in which the unwanted impurities are removed from the iron by reaction with oxygen gas. One of several methods used in steehnaking is the basic oxygen process. Because of its ease of operation and the relatively short time (about 20 minutes) required for each large-scale (hundreds of tons) conversion, the basic oxygen process is by far the most common means of producing steel today. 

This initiation step may occur in a number of ways by thermal decomposition of hydrocarbons with weak C-H bonds, by oxidation of hydrocarbons by metal ions via free radical routes, by reaction with oxygen gas, etc. 

Air cathodes are typically constructed in layers. The uppermost layer is exposed to the air and must allow oxygen gas to enter, so this material is a porous structure often made of PTFE (polytetrafluoroethylene). The catalysts are then found in the next layer. This layer is a porous carbon layer that contains the catalysts. This carbon layer can function on its own for reaction with oxygen gas, but the presence of catalysts can improve the performance of the cell. Catalysts are added to this layer as the pure catalyst itself or as a catalyst coated on carbon powder. This can be done with a wet or dry process. Depending on the wet process to manufacture the air cathode, the catalyst must be able to not decompose in the solvent such as water or alcohol. For the dry process the catalyst must readily mix with the carbon power and binders. Many air cathode manufacturing processes involve heat, some up to 300 °C, which requires thermal stability of the catalyst. The next layer down is a metal mesh current collector that is used to conduct the electrons and provide mechanical support. This air cathode represented here is typical of an air cathode manufactured by Yardney Technical Products Inc. and it has a second layer for catalysts. This second layer improves performance of the air cathode. 

Catalytic oxidation reactions in ionic liquids have been investigated only very recently. This is somewhat surprising in view of the well loiown oxidation stability of ionic liquids, from electrochemical studies [11], and the great commercial importance of oxidation reactions. Moreover, for oxidation reactions with oxygen, the nonvolatile nature of the ionic liquid is of real advantage for the safety of the reaction. While the application of volatile organic solvents may be restricted by the formation of explosive mixtures in the gas phase, this problem does not arise if a nonvolatile ionic liquid is used as the solvent. 

Reaction with oxygen occurs during combustion in an engine or furnace when the alkane is used as a fuel. Carbon dioxide and water are formed as products, and a large amount of heat is released. For example, methane (natural gas) reacts with oxygen according to the equation... 

Ammonia gas, NH3, can be burned with oxygen gas, Os, to give nitrogen gas, N2, and water, HsO. See if you can follow the logic of the following steps in balancing this reaction. 

At least since the mid-19th century, it has never been claimed that molecular nitrogen is completely unreactive with organic reagents. It was, however, known that many reactions that cannot be carried out in air because of reactions with oxygen, can be performed in a so-called inert atmosphere consisting of either a noble gas or — more cheaply — N2. This is common knowledge to the experimental chemist. 

H.15 Write a balanced equation for the complete combustion (reaction with oxygen) of liquid heptane, C7H)6, a component typical of the hydrocarbons in gasoline, to carbon dioxide gas and water vapor. 

H.20 The first stage in the production of nitric acid by the Ostwald process is the reaction of ammonia gas with oxygen gas, producing nitric oxide gas, NO, and liquid water. The nitric oxide further reacts with oxygen to produce nitrogen dioxide gas, which, when dissolved in water, produces nitric acid and nitric oxide. Write the three balanced equations that lead to the production of nitric acid. 

Every chemical reaction is accompanied by the transfer of energy as heat. For example, complete reaction with oxygen is called combustion and the combustion of methane, the major component of natural gas, is the following reaction ... 

The corrosion of iron occurs particularly rapidly when an aqueous solution is present. This is because water that contains ions provides an oxidation pathway with an activation energy that is much lower than the activation energy for the direct reaction of iron with oxygen gas. As illustrated schematically in Figure 19-21. oxidation and reduction occur at different locations on the metal surface. In the absence of dissolved ions to act as charge carriers, a complete electrical circuit is missing, so the redox reaction is slow, hi contrast, when dissolved ions are present, such as in salt water and acidic water, corrosion can be quite rapid. 

C19-0050. What are the half-reactions for these redox processes (a) Aqueous hydrogen peroxide acts on Co, and the products are hydroxide and Co , in basic solution, (b) Methane reacts with oxygen gas and produces water and carbon dioxide, (c) To recharge a lead storage battery, lead(II) sulfate is converted to lead metal and to lead(IV) oxide, (d) Zinc metal dissolves in aqueous hydrochloric acid to give ions and hydrogen gas. 

The Hj ion, recently detected in the interstellar medium via infrared transitions,25 can subsequently react with a variety of neutral atoms present in the gas. The reaction with oxygen leads to a chain of reactions that rapidly produce the hy-dronium ion H30+ via well-studied H atom-transfer reactions ... 

Nickel oxide, NiO, which adopts the sodium chloride structure (Fig. 1.14), can readily be made slightly oxygen rich, and, because the solid then contains more oxygen than nickel, the crystal must also contain a population of point defects. This situation can formally be considered as a reaction of oxygen gas with stoichiometric NiO, and the simplest assumption is to suppose that the extra oxygen extends the crystal by adding extra oxygen sites. Atoms are added as neutral atoms, and... 

Formaldehyde is stoichiometrically burned at constant pressure with oxygen (gas) to completion. C02 and H20, condensed as a liquid, are the sole products. The initial temperature before the reaction is 50 °C and the final temperature after its completion is 600 °C. Find, per mole of fuel, the heat transferred in the process, and state whether it is added or lost. Assume a constant specific heat of 35 J/mole K for all the species. Use Table 2.2 for all of your data. 

Gas phase thermal cracking of the volatiles occurs, reducing the levels of tar. Char (fixed carbon) and ash are the pyrolysis byproducts that are not vaporized. In the second step, the char is gasified through reactions with oxygen, steam, and hydrogen. Some of the unbumed char may be combusted to release the heat needed for the endothermic pyrolysis reactions. 

The Law of Conservation of Mass states that the total mass remains unchanged. This means that the total mass of the atoms of each element represented in the reactants must appear as products. In order to indicate this, we must balance the reaction. When balancing chemical equations, it is important to realize that you cannot change the formulas of the reactants and products the only things you may change are the coefficients in front of the reactants and products. The coefficients indicate how many of each chemical species react or form. A balanced equation has the same number of each type of atom present on both sides of the equation and the coefficients are present in the lowest whole number ratio. For example, iron metal reacts with oxygen gas to form rust, iron(III) oxide. We may represent this reaction by the following balanced equation ... 

It is possible that the as-made nanowires contain some crystalline Si core, and subsequent reaction with oxygen in the air results in the formation of silica nanowires. Since hydrogen gas was used in the reaction, pure silicon nanowires were probably made first, followed by oxidation in air. In the following discussion, for simplicity reason we will assume that amorphous SiNW were made during catal)Tic reactions. 

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