Is ammonia synthesis from nitrogen and hydrogen exothermic or endothermic reaction?

Upstairs gave the right data, but said it wrong.

The positive reaction is an exothermic reaction. The standard enthalpy becomes, and the minus sign indicates exothermy. In addition, the positive reaction is the entropy decrease, the standard entropy becomes s= j k mol, and the entropy you say never decreases is said to the isolated system, if you want to use it here, you have to calculate the entropy of the environment, and add it up with the entropy change of the system.

At the same time, the activation energy of this reaction is high, so although it is an exothermic reaction, it needs to be supplied with energy from the outside before the reaction can occur. Traditionally, this energy is supplied by external heating, and the use of catalysts in surface chemistry is precisely to reduce the need for external energy by releasing surface energy to allow the reaction to take place.

Endothermic reaction. 3) Ammonia synthesis compresses the pure hydrogen and nitrogen mixture to high pressure, and synthesizes ammonia under the action of a catalyst. Ammonia synthesis is the process of providing liquid ammonia products and is a core part of the entire ammonia production process.

The ammonia synthesis reaction is carried out under the conditions of higher pressure and the presence of catalyst, because the ammonia content in the gas after the reaction is not high, generally only 10% 20%, so the process of unreacted hydrogen and nitrogen circulation is adopted. The ammonia synthesis reaction formula is as follows:

n2+3h2→2nh3(g) =

Exothermic reaction, this reaction needs to be carried out at a temperature of 500 degrees Celsius, but not because it is an endothermic reaction, but because the catalyst used in this reaction needs to be at this temperature to maintain a large activity.

The ammonia synthesis reaction must provide high temperature and high pressure to be initiated, but after the reaction is completed, the total heat released is more than the heat absorbed, so it is an exothermic reaction.

Ammonia synthesis refers to the direct synthesis of ammonia by nitrogen and hydrogen under high temperature and high pressure and the presence of catalysts, which is a basic inorganic chemical process. In the modern chemical industry, ammonia is the main raw material for the fertilizer industry and basic organic chemicals.

Endothermic reaction. If you do more than one test paper, you will know! Hehe, some test papers tell you to calculate the reaction heat, which is an example of this question.

The reaction of nitrogen and oxygen is an endothermic reaction. The reaction conditions of nitrogen and oxygen are extremely harsh, and there is no reaction at room temperature, and a large amount of energy is required from discharge (nature) or high temperature (artificial) to react. If the reaction between the two is exothermic, then the heat released can provide the activation energy of the reaction to the surrounding molecules, causing the reaction to continue under the condition that no energy is supplied to the outside world.

Characteristics of nitrogenNitrogen makes up % of the total atmosphere (volume fraction) and is the main component of air. At standard atmospheric pressure, when cooled to, it becomes a colorless liquid, and when cooled, liquid nitrogen becomes a snow-like solid.

Nitrogen is chemically inactive, and it is difficult to react with other substances at room temperature, so it is often used to make preservatives. However, under high temperature and high energy conditions, it can undergo chemical changes with certain substances and be used to make new substances that are useful to human beings.

The above content refers to Encyclopedia - Nitrogen.

Exothermic.

The chemical equation of the industrial ammonia synthesis reaction is as follows: n 3h 2nh (catalyst, under high temperature and high pressure conditions) The reaction process uses iron catalyst (a catalyst mixed with iron as the main mixture), and the iron catalyst is most active at 500 °C, which is also the reason why the synthetic ammonia is selected at 500 °C.

The history of the development of synthetic ammonia.

The ammonia industry was formed in the early 20th century. In 1784, it was proved that ammonia is composed of nitrogen and hydrogen. In 1898, the use of carbonized re-beam calcium to absorb nitrogen to produce ammonia was successful.

At the end of the 19th century, after the progress made in the fields of thermodynamics, kinetics and catalysts, new progress was made in the study of ammonia synthesis reactions. In 1901, the French physical chemist Lu Chadley proposed that the conditions for ammonia synthesis should be high temperature, high pressure, and the existence of appropriate catalysts. In 1909, in the presence of a catalyst, nitrogen and hydrogen were directly synthesized from ammonia, and in 1912, a plant with a daily output of 30 tons was built.

The reaction of nitrogen and hydrogen is exothermic.

According to the thermochemical equation, if it is an exothermic reaction, then duh is "-", if it is an endothermic reaction, then h is "+", and the equation for the reaction of nitrogen and oxygen is n (g)+3h (g) 2nh (g) h=, where h is "+", which can be seen to be an exothermic reaction. The catalyst is an iron catalyst, and the reaction is reversible.

In addition, from the perspective of equilibrium movement, N2 + 3H2 = Catalysis = 2NH3, the volume of this reaction gas changes from four parts to two parts, and the internal energy is caused by the movement of molecules, so the number of molecules decreases, and the original internal energy is released, which is naturally an exothermic reaction.

The principle of equilibrium movement of the reaction between nitrogen and hydrogen is inescapable of Le Chatre's principle.

The result of the balance move - "I can't do it.""The outside world changes. If you increase the equilibrium movement by 1molH2, you may only consume a small part (the exact amount can be calculated using the equilibrium constant, and the proportion of hydrogen converted in the case of an increase in the total amount decreases, and the conversion rate decreases (the numerator and denominator increase at the same time, but the denominator increases more).

The ammonia synthesis reaction is an exothermic reaction.

But there is a question of activation energy involved.

This reaction must be high temperature and pressure to initiate the reaction, but the total heat released at the end of the reaction is more than the heat absorbed.

That is to say, it is exothermic.

The Haber method --- is a process of producing ammonia (NH3) from nitrogen and hydrogen.

Nitrogen and hydrogen are chemically reacted at 200 atmospheres at 400 degrees Celsius through a catalyst of iron compounds (Fe3+) to produce ammonia. In this case, the yield is generally 10-20%.

N2(g) +3H2(G) 2NH3(G) (The reaction is reversible).

Ho, the heat of reaction is kj mol.

The high temperature condition was chosen to increase the reaction rate, but because the reaction is exothermic, the yield after equilibrium under this condition is lower than that at lower temperature.

a) Preparation of raw materials.

1) The raw material for ammonia synthesis is nitrogen from air (obtained by fractionation of liquid air), and hydrogen is derived from water and fuel. The feed gas contains impurities, so the impurities need to be removed before participating in the reaction, i.e. the purification of the feed gas.

2) Preparation of hydrogen.

Natural gas (for its methane components), liquefied petroleum gas (for its propane and butane components) and petroleum (for its hydrocarbons such as naphtha) can be used to make hydrogen for ammonia synthesis.

The first step is to remove the sulfides from the feedstock, as the sulfides can poison the catalyst used in the Haber-Bosch process. Catalytic hydrogenation can turn organic sulfides into hydrogen sulfide:

h2 + rsh → rh + h2s(g)

The hydrogen sulfide produced is absorbed by the zinc oxide and becomes water and zinc sulfide:

h2s + zno → zns + h2o

Catalyzed by nickel, it reacts with water and converts desulfurized hydrocarbons (such as methane) into a mixture of hydrogen and carbon monoxide

ch4 + h2o → co + 3 h2

CO + H2O CO2 + H2 (reversible reaction).

The carbon dioxide can then be absorbed by a 2-aminoethanol solution or removed using pressure swing adsorption (PSA), where a patented solid-state adsorption medium is used.

The final step in hydrogen production is the removal of small amounts of carbon monoxide and carbon dioxide from hydrogen by methanation using a catalyst

co + 3 h2 → ch4 + h2o

co2 + 4 h2 → ch4 + 2 h2o

Water vapor recombination, carbon monoxide shift, carbon dioxide removal and methanation are performed at pressures of 25 to 35 Pa.