Chemistry of Selected Metals and their Compounds (Cont'd)

Grade 12 · Chemistry

Semester 2 | Period 4 | Week 22

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Subject: Chemistry

Semester: 2

Period: 4

Week: 22

School Name:
Teacher’s Name:
Subject: Chemistry
Grade Level: Grade 12
Week & Period: Week 22, Period IV
Date:

Topic: Chemistry of Selected Metals and Their Compounds (cont’d)
Subtopics:

  • Nitrogen and its compounds
  • Industrial preparation and uses of nitrogen
  • Properties and industrial preparation of ammonia and nitric acid
  • Reactions and uses of nitrogen compounds

 

Learning Objectives:
By the end of the lesson, learners should be able to:

  1. Describe nitrogen gas and its occurrence.
  2. Explain the industrial method of obtaining nitrogen from liquified air.
  3. Outline the laboratory and industrial preparation of ammonia and nitric acid.
  4. State the physical and chemical properties of ammonia and nitric acid.
  5. Discuss the uses of ammonia, nitric acid, and trioxonitrate (V) salts.
  6. Illustrate reactions of ammonia and nitric acid in chemical equations.

 

Previous Knowledge:
Students have learned about air as a mixture of gases and basic reactions of acids and bases.

 

Instructional Materials:

  • Nitrogen cycle chart
  • Diagram of fractional distillation of air
  • Haber process and Ostwald process diagrams
  • Samples or images of fertilizers and explosives
  • Videos or simulations of ammonia preparation

 

Anticipation (Warm-Up) – 5 minutes:
Ask: “What is the importance of nitrogen to plants and humans? Can nitrogen form acids or bases?”

 

Building Knowledge (Main Lesson) – 25 minutes:

  1. Overview of Nitrogen:
    • Makes up about 78% of air by volume.
    • Chemically inert under normal conditions.
    • Essential for amino acids and nucleic acids.
  2. Industrial Preparation of Nitrogen:
    • Obtained from liquified air through fractional distillation.
    • Boiling point of nitrogen: −196°C, separated before oxygen (−183°C).
  3. Preparation of Ammonia (NH₃):
    • Haber Process: N₂ + 3H₂ ⇌ 2NH₃ (reversible, exothermic, uses iron catalyst).
    • Carried out under high pressure (~200 atm) and temperature (450°C).
    • Ammonia is a colorless gas with a pungent smell; very soluble in water.
  4. Uses of Ammonia:
    • Fertilizer production (ammonium nitrate, urea).
    • Cleaning products and nitric acid production.
  5. Preparation of Nitric Acid (HNO₃):
    • Ostwald Process:
      • NH₃ is oxidized to NO, then to NO₂, and finally dissolved in water to form HNO₃.
      • Catalysts: Platinum or Rhodium.
    • Strong oxidizing acid.
  6. Uses of Nitric Acid:
    • Fertilizers, explosives (TNT), dyes, and plastics.
    • Forms salts known as nitrates (e.g. KNO₃, NaNO₃).

 

Learners’ Activities:

  • Complete a diagram labeling the Haber process.
  • Match reactions with respective nitrogen compounds.
  • Group discussion: Importance of nitrogen-based fertilizers vs. environmental impact.

 

Consolidation (Review and Assessment) – 10 minutes:

  • Quick quiz: Fill-in-the-blanks on nitrogen cycle and reactions.
  • Group discussion: Pros and cons of using ammonia-based fertilizers in Liberia.

Homework / Assignment:

  • Write a report comparing ammonia and nitric acid in terms of preparation, reactions, and uses.
  • Prepare flashcards on the steps of the Haber and Ostwald processes.

 

Notes – Detailed and Explained:

Nitrogen is a major component of the atmosphere and an essential element in biological molecules. However, due to its strong triple bond (N≡N), it is relatively inert and must be converted into reactive forms for practical use.

The industrial preparation of nitrogen involves fractional distillation of liquified air. This process utilizes the different boiling points of gases to isolate nitrogen, which is then used in various chemical industries.

Ammonia (NH₃) is produced industrially using the Haber process, where nitrogen reacts with hydrogen under high pressure and temperature in the presence of an iron catalyst. Ammonia has numerous uses, especially in agriculture as a fertilizer and in the production of other nitrogen-containing compounds.

Nitric Acid (HNO₃) is obtained through the Ostwald process, which involves the catalytic oxidation of ammonia to nitrogen oxides, followed by absorption in water. Nitric acid is a strong acid and oxidizing agent used in fertilizer production and the manufacture of explosives.

Trioxonitrate (V) salts, commonly referred to as nitrates, are derived from nitric acid. These salts are soluble and serve as plant nutrients and oxidizers.

 

Expanded Notes / Instructions:

  • Draw parallels between Liberia’s agricultural needs and the importance of nitrogen-based fertilizers.
  • Explore local methods of organic nitrogen enrichment versus industrial fertilizers.
  • Discuss the environmental impact of nitrogen pollution, especially eutrophication and acid rain.

 

Inclusive / Differentiation:

  • Use visual charts for visual learners.
  • Provide scaffolding for low-literacy learners (e.g., matching terms and pictures).
  • Allow high-achievers to present on industrial nitrogen usage in global farming.

 

Teacher’s Reflection (Post-Lesson Questions):

  • Did learners understand the processes and relevance of ammonia and nitric acid?
  • Could learners connect chemical industry to agricultural practices?
  • Were learners able to explain both preparation methods and environmental impact?