Process Haber

My favorite reaction is the Haber process, the synthesis of ammonia from nitrogen and hydrogen gases. After balancing the reaction (see the section Balancing the Haber process, earlier in this chapter), you end up with 

Written this way, the reaction says that hydrogen and nitrogen react to form ammonia — and this keeps on happening until you use up one or both of the reactants. But this isn t quite true. 

If this reaction occurs in a closed container (which it has to, with everything being gases), then the nitrogen and hydrogen react and ammonia is formed — but some of the ammonia soon starts to decompose into nitrogen and hydrogen, like this  

In the container, then, you actually have two exactly opposite reactions occurring — nitrogen and hydrogen combine to give ammonia, cuid ammonia decomposes to give nitrogen and hydrogen. 

Instead of showing the two separate reactions, you can show one reaction cUid use a double arrow like this  

The vast scale on which the industrial production of NH3 is carried out and its growth over the latter part of the 20th century was illustrated in Box 15.3. In eq. 15.21 and the accompanying discussion, we described the manufacture of NH3 using a heterogeneous catalyst. Now we focus on the mechanism of the reaction and on catalyst performance. 

Without a catalyst, the reaction between N2 and H2 occurs only slowly, because the activation barrier for the dissociation of N2 and H2 in the gas phase is very high. In the presence of a suitable catalyst such as Fe, dissociation of N2 and H2 to give adsorbed atoms is facile, with the energy released by the formation of M-N and M—H bonds more than offsetting the energy required for N=N and H—H fission. The adsorbates then readily combine to form NH3 which desorbs from the surface. The rate-determining step is the dissociative adsorption of N2 (eq. 25.35). The notation (ad) refers to an adsorbed atom. 

Dihydrogen is similarly adsorbed (eq. 25.30), and the surface reaction continues as shown in scheme 25.36 with 

What factors contribute towards this trend  

In 2009, 130 Mt of NH3 (the mass is in terms of nitrogen content) were manufactured worldwide. Production has increased dramatically over the last 40 years. Account for the scale of production in terms of the uses of NH3. 

The catalytic activity of various metals with respect to the 

Write equations to show how H2 is manufactured for use in the Haher process. [Ans. See scheme 10.12  

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Haber process The process for the direct synthesis of ammonia from and Hj over a catalyst. 

This reaction is an undesirable side reaction in the manufacture of hydrogen but utilised as a means of removing traces of carbon monoxide left at the end of the second stage reaction. The gases are passed over a nickel catalyst at 450 K when traces of carbon monoxide form methane. (Methane does not poison the catalyst in the Haber process -carbon monoxide Joes.)... 

The process is as follows ammonia gas (made by the Haber process) is liquefied under pressure, to freeze out any water, and the anhydrous gas is then passed together with dust-free air through a... 

Although the left to right reaction is exothermic, hence giving a better equilibrium yield of sulphur trioxide at low temperatures, the reaction is carried out industrially at about 670-720 K. Furthermore, a better yield would be obtained at high pressure, but extra cost of plant does not apparently justify this. Thus the conditions are based on economic rather than theoretical grounds (cf Haber process). 

Ammonia (NH3) is the most important commercial compound of nitrogen. It is produced by the Haber Process. Natural gas (methane, CH4) is reacted with steam to produce carbon dioxide and hydrogen gas (H2) in a two step... 

Industrially, production is either from the Haber process at high pressure ... 

An even more effective homogeneous hydrogenation catalyst is the complex [RhClfPPhsfs] which permits rapid reduction of alkenes, alkynes and other unsaturated compounds in benzene solution at 25°C and 1 atm pressure (p. 1134). The Haber process, which uses iron metal catalysts for the direct synthesis of ammonia from nitrogen and hydrogen at high temperatures and pressures, is a further example (p. 421). 

It is estimated that each year approximately 150 million tonnes of nitrogen are fixed biologically compared to 120 million tonnes fixed industrially by the Haber process (p. 421). In both cases N2 is converted to NH3, requiring the rupture of the N=N triple bond which has the highest dissociation energy (945.41 kJmol )... 

Haben, n. Com.) credit creditor. Haberverfahren, n. Haber process. 

The Haber process, represented by this equation, is now the main source of fixed nitrogen. Its feasibility depends on choosing conditions under which nitrogen and hydrogen react rapidly to give a high yield of ammonia. At 25°C and atmospheric pressure, the position of the equilibrium favors the formation of NH3 (K= 6 x 105). Unfortunately. however, the rate of reaction is virtually zero. Equilibrium is reached more rapidly by raising the temperature. However, because... 

Effect of Temperature and Pressure on the Yield of Ammonia in the Haber Process (PH2 = 3PNl)... 

Ammonia is one of the most important industrial chemicals more than ten million tons of NH3 are produced annually in the United States. You will recall (Chapter 12) that it is made by the Haber process... 

Haber process An industrial process used to make ammonia from the elements, 342-343,559-560... 

In an important industrial process for producing ammonia (the Haber Process) the overall reaction is... 

Ammonia a base, 184 boiling point, 64 complexes, 392, 395, 408 complex with Ag+, 154 Haber process for, 150 and hydrogen chloride, 24 model of, 21 molar volume. 60, 64 production, 150 P V behavior of, 19, 51, 60 solubility, 20 Ampere, 241 Amphoteric, 371 complexes, 396 Analogy... 

H+], calculation of, 192, see also Hydrogen ion Haber, Fritz, 151 Haber process, 140, 150 Hafnium, oxidation number, 414 Haldane, J. B. S., 436 Half-cell potentials effect of concentration, 213 measuring, 210 standard, 210 table of, 211, 452 Half-cell reactions, 201 Half-life, 416 Half-reaction, 201 balancing, 218 potentials, 452 Halides... 

The Haber process for the synthesis of ammonia is one of the most significant industrial processes for the well-being of humanity. It is used extensively in the production of fertilizers as well as polymers and other products, (a) What volume of hydrogen at 15.00 atm and 350.°C must be supplied to produce 1.0 tonne (1 t = 10 kg) of NH3 (b) What volume of hydrogen is needed in part (a) if it is supplied at 376 atm and 250.°C ... 

FIGURE 9.17 The Haber process is still used to produce almost all the ammonia manufactured in the world. This pie chart shows how the ammonia is used. The figures are percentages. Note that 80%— as shown by the green band—is used as fertilizer, either directly or after conversion into another compound. 

Haber process for ammonia. Another is finely divided vanadium pentoxide, V205, which is used in the contact process for the production of sulfuric acid ... 

The reactant is adsorbed on the catalyst s surface. As a reactant molecule attaches to the surface of the catalyst, its bonds are weakened and the reaction can proceed more quickly because the bonds are more easily broken (Fig. 13.36). One important step in the reaction mechanism of the Haber process for the synthesis of ammonia is the adsorption of N2 molecules on the iron catalyst and the weakening of the strong N=N triple bond. 

Each year, about half the 3 X 108 kg of hydrogen used in industry is converted into ammonia by the Haber process (Section 9.12). Through the reactions of ammonia, hydrogen finds its way into numerous other important nitrogen compounds such as hydrazine and sodium amide (see Section 15.2). 

By far the most important hydrogen compound of a Group 15/V element is ammonia, NH., which is prepared in huge amounts by the Haber process. Small quantities of ammonia are present naturally in the atmosphere as a result of the... 

Haber process (Haber-Bosch process) The catalyzed synthesis of ammonia at high pressure, half-cell One compartment of an electrochemical cell consisting of an electrode and an electrolyte, half-life (f1/2) (1) In chemical kinetics, the time needed for... 

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