Ammonia has the chemical formula NH3 and is a colorless gas. It is made of hydrogen and nitrogen. In its liquid state, it is known as ammonium hydroxide. This inorganic chemical has an unpleasant odor. It is hazardous and corrosive in its concentrated form.
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Joseph Black (Scotland), Peter Woulfe (Ireland), Carl Wilhelm Scheele (Sweden/Germany), and Joseph Priestley isolated ammonia in the 18th century (England). Claude Louis Berthollet, a French chemist, determined its elemental composition in 1785. It is an odorless, toxic gas with no visible hue. It has been identified in space and happens naturally as a result of the anaerobic degradation of plant and animal waste. In conjunction with rhizobia bacteria, certain plants, particularly legumes, “fix” atmospheric nitrogen to make ammonia.
Ammonia Chemistry Questions with Solutions
Q1. The chemical formula of ammonia is-
a.) NH2
b.) NH3
c.) NH4
d.) NH5
Correct Answer– (b.) NH3.
Q2. Which of the following cation does not form an amine complex with an excess of ammonia?
a.) Al3+
b.) Cd2+
c.) Ag+
d.) Cu2+
Correct Answer– (a.) Al3+
Q3. The catalyst used in the Haber process for manufacturing ammonia is-
a.) Pt
b.) Fe + Mo
c.) CuO
d.) Al2O3
Correct Answer– (b.) Fe + Mo
Q4. Ammonia gas is collected by-
a.) Upward displacement of water
b.) Upward displacement of air
c.) Downward displacement of water
d.) Downward displacement of air
Correct Answer– (d.) Downward displacement of air
Q5. ___ fumes confirm the presence of ammonia gas.
a.) Dense Red
b.) Dense White
c.) No fumes
d.) None of the above
Correct Answer– (b.) Dense White
A glass rod dipped in HCl is brought near the mouth of the gas jar through which white dense fumes can be seen which confirms the presence of ammonia gas.
Q6. Why ammonium nitrate is not used in the preparation of ammonia?
Answer. Ammonium nitrate is not used in the preparation of ammonia because it is explosive and may itself decompose and form a nitrous oxide and water vapor.
Q7. In the preparation of ammonia, why are solid ammonium chloride and slaked lime is taken in the ratio of 2:3 by weight?
Answer. Solid ammonium chloride is a sublimable solid which could be lost due to direct heating. Therefore, to counteract the loss of ammonium chloride by sublimation the higher ratio of slaked lime is taken.
Q8. Fill in the blank.
An aqueous solution of ammonia is used for identifying ___.
Answer. An aqueous solution of ammonia is used for identifying cations.
When ammonia is dissolved in water, it produces ammonium hydroxide. In excess NH4OH, ammonium hydroxide reacts with metallic salt solutions to form insoluble precipitates of their respective metallic hydroxides, which vary in color and solubility.
Q9. How is ammonia gas dried?
Answer. Ammonia gas can be dried by using a drying agent such as quick lime (CaO). It is basic in nature and does not react with NH3 which is also basic.
Q10. Why ammonia gas is not collected over water?
Answer. Ammonia is not collected over water because it is highly soluble in water.
Q11. Define liquor ammonia.
Answer. A saturated ammonia solution in water is known as liquor ammonia fortis. NH3 represents the chemical formula for liquid ammonia. The chemical formula for liquid ammonia fortis is NH4OH. As a cleaning agent and emulsifier, liquid ammonia is utilized.
Q12. How can ammonia be separated from nitrogen and hydrogen?
Answer. A mixture of ammonia, residual nitrogen, and hydrogen is allowed to rapidly expand via a tiny nozzle into a low-pressure zone while under pressure. This creates a drop in temperature, which liquefies easily liquefiable NH3 gas while making it difficult to liquefy nitrogen and hydrogen.
Q13.Write your observation when ammonia gas is made to pass through-
(i) moist red litmus paper
(ii) Methyl orange solution
(iii) Phenolphthalein
Answer. When ammonia gas is made to pass through-
(i) moist red litmus paper – The moist litmus paper will turn blue
(ii) Methyl orange solution – It turns methyl orange to yellow.
(iii) Phenolphthalein – It turns phenolphthalein from colorless to pink.
Q14. Give a few large-scale applications of ammonia.
Answer. Some of the uses of ammonia are as follows-
- Nearly 80% of industrially produced ammonia is used as fertilizer in agriculture.
- Ammonia is also used to cleanse water as a refrigerant gas.
- It is utilized in the production of plastics, explosives, textiles, insecticides, and various other compounds.
- It is utilized in the production of other ammonium compounds, including ammonium chloride, ammonium carbonate, and ammonium sulfate, among others.
Q15. Give the preparation of ammonia by Haber’s process.
Answer. In the Haber process, “the atmospheric nitrogen (N2) is converted to ammonia (NH3) by reacting it with hydrogen (H2)”. Here a metal catalyst is used and high temperatures and pressures are maintained.
The raw materials for the process are
- Air, which supplies the nitrogen.
- Natural gas and water supply the hydrogen and the energy needed to heat the reactants.
- Iron is the catalyst and does not get used up.
Preparation-
- By volume, nitrogen gas is extracted from the air and mixed with hydrogen atoms extracted from natural gas in the Haber process.
- The gases are circulated through four catalyst beds, with each pass resulting in cooling. This is done to maintain a constant equilibrium.
- While variable levels of conversion take place during each pass in which unreacted gases are recycled,
- Typically, an iron catalyst is utilized, and the entire procedure is carried out at a temperature of 400 – 450 °C and a pressure of 150 – 200 atm.
- In addition, the process includes shift conversion, carbon dioxide removal, steam reformation, and methanation.
- Finally, the ammonia gas is cooled to produce a liquid solution, which is then collected and stored in containers.
