22.3.1 Nitrogen

Question 1

Nitrogen

Answer 1

• The Haber-Bosch process is used to produce ammonia from nitrogen and hydrogen.
• The Ostwald process is used to produce nitric acid from ammonia.
• Nitric acid is produced from nitrogen monoxide gas in the atmosphere, forming acid rain.
• The Raschig process is used to produce hydrazine, which can act as either a reducing agent or an oxidizing agent.

Question 2

note 1

Answer 2

• About 78% of the gases in air are dinitrogen (N 2 ). However, the triple bond between the two nitrogen molecules is difficult to break.
• The Haber-Bosch process is used to produce ammonia (NH 3 ) from nitrogen gas (N 2 ) and hydrogen gas (H 2 ). This reaction is exothermic and extremely slow. Heating up the mixture speeds up the reaction, but favors the reactants.
• An iron-aluminum catalyst is used to speed up the reaction. However, reactants are still favored over products.
• Le Châtelier’s principle is used to drive the process.
  Ammonia is constantly removed, causing the equilibrium to shift toward products. Ammonia has a much higher boiling point than hydrogen or nitrogen, and can therefore be easily collected by cooling the reaction mixture.
• The Ostwald process is used to produce nitric acid from ammonia.
• First, ammonia is burned in the presence of a platinum
  catalyst, producing nitric oxide (nitrogen monoxide, NO).
  Nitric oxide then reacts with more oxygen (O 2 ) to produce nitrogen dioxide (NO 2 ). Finally, nitrogen dioxide reacts with water (H 2 O) to produce nitric acid (HNO 3 ) and additional nitric oxide. The additional nitric oxide is circulated into step two.
• The nitric acid produced in the Ostwald process can be reacted with ammonia to produce ammonium nitrate (NH 4 NO 3 ), which is used in fertilizers. Ammonium nitrate can be heated to produce nitrous oxide (dinitrogen monoxide, N 2 O), which is used as an anesthetic

Question 3

note 2

Answer 3

• Nitrogen reacts with oxygen in the engines of cars, producing nitric oxide.
• The catalytic converter of the car converts nitric oxide back to nitrogen and oxygen. However, if the nitric oxide escapes without being converted, it may further oxidize in the atmosphere to produce nitrogen dioxide. The nitrogen dioxide can react with water, producing nitric acid. This nitric acid is a source of acid rain.
• In the Raschig process, hypochlorite ion (OCl – ) is used to oxidize ammonia to form hydrazine (N 2 H 4 ). Hydrazine has chemical properties similar to hydrogen peroxide, and can act as either a reducing agent or an oxidizing agent.
• The reaction of hydrazine with oxygen is very exothermic. For this reason, hydrazine is used as rocket fuel. Hydrazine can also react with dinitrogen tetroxide (N 2 O 4 ). This reaction produces even more energy than the reaction of hydrazine with oxygen.
• Hydrazine is also used to treat wastewater. Hydrazine can react with halogens (such as chlorine) in wastewater, forming nitrogen gas and HX, where X is the halogen.

Question 4

Which of the following compounds contains nitrogen in its highest oxidation state?

Answer 4

Dinitrogen pentoxide

Question 5

During the Haber-Bosch process, ammonia must be continuously removed from the reaction chamber in order to facilitate the production of more ammonia. What chemical rule or principle does this illustrate?

Answer 5

Le Châtelier’s principle

Question 6

Which industrial process is used to “activate” nitrogen?

Answer 6

Haber-Bosch process

Question 7

Identify and arrange in the correct order the steps involved in the process of producing nitric acid using the Ostwald method.

1. 2NO + O2	 → 	2NO2
2. 4NH3 + 5O2	 → 	4NO + 6H2O
3. 3NO2 + 3H2O	 → 	2HNO3 + NO
4. NH3 + 2O2	 → 	HNO3 + H2O

Answer 7

2, 1, 3

Question 8

Which of the following nitrogen-containing substances has been used as rocket fuel?

Answer 8

N2H4

Question 9

What is the general term for the removal of elemental nitrogen from the atmosphere?

Answer 9

Nitrogen fixation

Question 10

Which of the following is not a source or method of nitrogen fixation?

Answer 10

The oxidation of hydrazine

Question 11

Ammonium nitrite decomposes upon heating into nitrogen gas and water. How much nitrogen gas is produced when 3.00 grams of solid ammonium nitrite is heated at 235°C and 1.10 atm?

Answer 11

1.78 L

Question 12

Ammonia (NH3 ) : hydrazine (N2H4 ) ::

methane (CH4 ) : ____________________.

Answer 12

ethane (CH3CH3 )

Question 13

Which of the following statements concerning nitrogen is false?

Answer 13

Nitrogen is abundant in the lithosphere.