Preparation And Properties Of Ammonia

Introduction

Imagine entering the kitchen and opening one of the bottles with the household cleaner. One will smell a strong smell with a bad odor. Most likely, ammonia is going to be the compound. For sure, this is one of those compounds which significantly shapes our daily lives. Of course not only as a household cleaning reagent. Ammonia finds its invaluable application in agriculture and industry. It is applied in fertilizers for food, and in a wide range of industrial processes, for example, plastics, explosives, and textile manufacture. In this paper we examine the preparation and properties of ammonia, outline its chemical features, means of production, and very broad application.

Ammonia

Ammonia is a colorless gas, and it has a typical pungent smell. Ammonias are one nitrogen atom bonded with three hydrogen atoms chemically, NH3. This is a very simple and very interesting molecule because of its polarity and the possibility of hydrogen bonding. The independence and corollaries of the very same polar nature and hydrogen bonding make ammonia highly soluble in water by forming ammonium hydroxide on dissolution, NH4OH. This thereby made possible ground for the remainder of the work on its applications and preparation methods because it brings into play knowledge of the overall chemical structure and properties of ammonia.

Preparation Methods

The Haber-Bosch process offers a significant method of preparation for ammonia and was developed in the early twentieth century, whereby it greatly revolutionized agriculture and industry. The process maintained for the same is basically the direct combination of nitrogen in the air with high pressure and temperature in the presence of an iron catalyst. This reaction is made use of a well-balanced chemical equation as follows:
N₂(g) + 3H₂(g) → 2NH₃(g)
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] Another process involves heating ammonium salts; for instance, ammonium chloride, upon reaction with a strong base, such as calcium hydroxide, in another to produce the ammonia gas. All these different processes indicate just how urgent the production of ammonia is for the realized ends of industry and for chemical purposes; thus, they only amount to just how much chemistry and engineering meet.

Preparation
Ammonia is present in small quantities in air and soil where it is formed by the decay of nitrogenous organic matter e.g., urea.

$\mathrm{NH}_2 \mathrm{CONH}_2+2 \mathrm{H}_2 \mathrm{O} \rightarrow\left(\mathrm{NH}_4\right)_2 \mathrm{CO}_3 \rightleftharpoons 2 \mathrm{NH}_3+\mathrm{H}_2 \mathrm{O}+\mathrm{CO}_2$

On a small scale, ammonia is obtained from ammonium salts which decompose when treated with caustic soda or calcium hydroxide.

$\begin{aligned} & 2 \mathrm{NH}_4 \mathrm{Cl}+\mathrm{Ca}(\mathrm{OH})_2 \rightarrow 2 \mathrm{NH}_3+2 \mathrm{H}_2 \mathrm{O}+\mathrm{CaCl}_2 \\ & \left(\mathrm{NH}_4\right)_2 \mathrm{SO}_4+2 \mathrm{NaOH} \rightarrow 2 \mathrm{NH}_3+2 \mathrm{H}_2 \mathrm{O}+\mathrm{Na}_2 \mathrm{SO}_4\end{aligned}$

On a large scale, ammonia is manufactured by Haber’s process.

N₂(g) + 3H₂(g) → 2NH₃(g)

In accordance with Le Chatelier’s principle, high pressure would favor the formation of ammonia. The optimum conditions for the production of ammonia are a pressure of 200 × 10⁵ Pa (about 200 atm), a temperature of ~ 700 K, and the use of a catalyst such as iron oxide with small amounts of K₂O and Al₂O₃ to increase the rate of attainment of equilibrium. The flow chart for the production of ammonia is shown in the figure given below. Earlier, iron was used as a catalyst with molybdenum as a promoter.

Properties
Ammonia is a colorless gas with a pungent odor. Its freezing and boiling points are 198.4 and 239.7 K respectively. In the solid and liquid states, it is associated through hydrogen bonds as in the case of water and that accounts for its higher melting and boiling points than expected on the basis of its molecular mass. The ammonia molecule is trigonal pyramidal with the nitrogen atom at the apex. It has three bond pairs and one lone pair of electrons as shown in the structure. Ammonia gas is highly soluble in water. Its aqueous solution is weakly basic due to the formation of OH^–ions.

$\mathrm{NH}_3(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightleftharpoons \mathrm{NH}_4^{+}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq})$

It forms ammonium salts with acids, e.g., NH₄Cl, (NH₄)₂SO₄, etc. As a weak base, it precipitates the hydroxides (hydrated oxides in the case of some metals) of many metals from their salt solutions. For example,

$\begin{aligned} & \mathrm{ZnSO}_4(\mathrm{aq})+2 \mathrm{NH}_4 \mathrm{OH}(\mathrm{aq}) \rightarrow \mathrm{Zn}(\mathrm{OH})_2(\mathrm{~s})+\left(\mathrm{NH}_4\right)_2 \mathrm{SO}_4(\mathrm{aq}) \\ & \mathrm{FeCl}_3(\mathrm{aq})+\mathrm{NH}_4 \mathrm{OH}(\mathrm{aq}) \rightarrow \mathrm{Fe}_2 \mathrm{O}_3 \cdot \mathrm{xH}_2 \mathrm{O}(\mathrm{s})+\mathrm{NH}_4 \mathrm{Cl}(\mathrm{aq})\end{aligned}$

The presence of a lone pair of electrons on the nitrogen atom of the ammonia molecule makes it a Lewis base. It donates the electron pair and forms a linkage with metal ions and the formation of such complex compounds finds applications in the detection of metal ions such as Cu²⁺, and Ag⁺.

Uses

• Ammonia is used to produce various nitrogenous fertilizers (ammonium nitrate, urea, ammonium phosphate, and ammonium sulfate)
• It is used in the manufacture of some inorganic nitrogen compounds, the most
  important one being nitric acid.
• Liquid ammonia is also used as a refrigerant.

Relevance and Applications
Any other major application of ammonia involves agriculture. It is used in the production of ammonia-based fertilizers such as urea, ammonium nitrate, and ammonium sulfate. These fertilizers are in high demand, as they are supposed to improve the yields of crops in order to be guaranteed bountiful harvests for food production. Applications of ammonia occur in the industrial sector concerned with the production of nitric acid. It also finds application in refrigerating systems as ammonia absorbs heat well.

This small molecule of ammonia contains a large number of hydrogen bondings. Research for its different applications thus falls under the realms of inorganic and physical chemistry. It also has a very major role in the nitrogen cycle and its related impacts on the environment, more so around its release from agricultural activities, and thereafter what impacts it has caused in turn, for example, on ecosystems. These many uses underpin the importance to which application and study are placed in the science of ammonia.

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Some Solved Examples

Example 1
Question: How many isomeric disubstituted borazines B₃N₃H₄X₂ are possible?

Solution: Disubstituted borazine has 4 isomers: Ortho, meta-1, meta-2, and para isomers. Therefore, the number of possible isomers is 4.

Example 2
Question: What is the favorable condition for the formation of NH3?

Solution: The reaction for the formation of ammonia is:
N₂(g) + 3H₂(g) → 2NH₃(g)
The reaction is exothermic, so a favorable condition is a low temperature. Additionally, increasing the pressure shifts the equilibrium in the direction of fewer gaseous moles. Since the number of gaseous moles decreases on the right-hand side, the favorable condition will be high pressure. Therefore, the correct condition is low temperature and high pressure.

Example 3
Question: What are the products formed in the following reaction?
CaCN₂ + 3H₂O ${\rightarrow}$

Solution: The reaction for the hydrolysis of calcium cyanamide (CaCN₂) with water is:

CaCN₂ + 3H₂O ${\rightarrow}$ CaCO₃ + 2NH₃
Therefore, the products formed are calcium carbonate (CaCO₃ and ammonia (NH₃).

Summary

From being merely one of the very pungent elements that make for household cleaners to an immense service given globally and industrially is ammonia. It is critical to perform discussions on the preparation of ammonia via the Haber-Bosch process and the reaction of ammonium salts with a base. From fertilizers, through industry, to research in academics, such are its endless applications. A foothold of information about the preparation and properties of ammonia will outline the chemical character of the compound and set forth quite cogent arguments for the utility value in a number of various fields.