Nitrogen and hydrogen to ammonia

This phenomenon is well illustrated using the conversion of nitrogen and hydrogen to ammonia by the Haber Process ... 

An important consequence of (2.3) is if for a system the rate constant is known for the forward reaction, the rate constant for the backward reaction can be calculated. For example, the rate of the reaction between nitrogen and hydrogen to ammonia is difficult to determine, but can easily be derived from the rate of the ammonia decomposition and the equilibrium constant for this reaction. 

The Haber process is used in industry to convert nitrogen and hydrogen to ammonia. The formation of ammonia gas is exothermic. 

Let me start with a simple case the conversion of nitrogen and hydrogen to ammonia. On the one hand, it is a complex reaction and we do not know the mechanism. On the other hand, with reasonable effort we can get an all-purpose M, a rate relation accurate enough so that we do not have to ask about its use. Such expressions are not necessarily unique. Ferrari (45) lists 24 rate expressions of the form... 

The Haber process is the reaction of nitrogen and hydrogen to produce ammonia. The two elements nitrogen and hydrogen are reacted over an iron catalyst under 200 atm, at 450 °C to produce ammonia. 

Fritz Haber was born on December 9, 1868 in Breslau, Germany. Haber s research work (1905-1911) on the equilibrium between nitrogen and hydrogen to form ammonia by establishing the exact temperature and pressure, as well as the catalyst to produce the compound. 

PI5.1 Show that in reaction (15.1), assuming ideal behavior of the gases, the maximum (equilibrium) conversion of nitrogen and hydrogen into ammonia at a given temperature and total pressure, is obtained when the reacting gases are in the proportion of 1 to 3. (To do so, suppose that the N2 and H2 molecules are present in the ratio of 1 to r, with x as the mole fraction of NH3 present at equilibrium. Then express Kp in terms of mole fractions and the total pressure, and find the condition that makes dx/dr equal to zero.)... 

Write an equilibrium constant expression for the reaction of nitrogen and hydrogen to form ammonia at 500°C. 

Phosphine, Phosphonitun Salts.—It will be recalled from our study of inorganic chemistry that phosphorus forms a compound with hydrogen analogous to the nitrogen and hydrogen compound ammonia, NH3. It is given the formula in the gaseous state of PH3, and is called phosphine. This compound like ammonia forms salts with acids that are known as phosphonitun salts. 

For instance, the reaction between nitrogen and hydrogen to produce ammonia can be represented by the equation ... 

The reaction between nitrogen and hydrogen to produce ammonia... 

It may seem to be a backward step to have prepared ammonia from nitrogen and hydrogen, to then burn the ammonia to obtain nitric oxide. However, if one considers the endothermic nature of the reaction between nitrogen and oxygen (Eq. 11.37), it becomes apparent why nitric oxide yields, even at carbon arc temperatures of around 3,000°C, are only a few volume percent. 

Indeed, Antoine Lavoisier named nitrogen gas azote," meaning vvi life," because it is so unreactive. Nevertheless, the conversion of nitrogen and hydrogen to form ammonia is thermodynamically favorable the reaction is difficult kinetically because intermediates along the reaction pathway are unstable. 

Many important reactions, such as the conversion of atmospheric nitrogen and hydrogen into ammonia, are very slow and remain that way tmtil a catalyst (in this case iron oxide) is identified. In our bodies, enzymes can function as catalysts to speed up essential reactions. In order to tmderstand reaction mechanisms, chemists focus on discrete reaction steps and often need very short-term experimental methods to follow rates of individual reaction steps. For instance, Manfred Eigen and Leo De Maeyer (1955) used an electrical conductance relaxation method to measure the rate of the reaction... 

The same holds true if carbon and hydrogen from Arbitrary 3 are reacted to form methane, or nitrogen and hydrogen to form ammonia. 

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