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Subject: Chemistry
Semester: 1
Period: 3
Week: 15
School Name:
Teacher’s Name:
Subject: Chemistry
Grade Level: Grade 11
Week & Period: Week 15, Period III
Date:
Topic: Acid-Base Properties of Salts and Lewis Acids/Bases
Sub-topic:
- Acid-base properties of salts
- Laboratory and industrial preparation of salts
- Chemicals from sodium chloride solution
- Hydrolysis of salts
- Properties of Lewis acids and bases
Learning Objectives
By the end of the lesson, learners should be able to:
- Explain how salts affect pH of a solution
- Describe how salts are prepared in laboratories and industries
- Discuss the hydrolysis of salts and its implications
- Identify Lewis acids and bases and describe their properties
Previous Knowledge
Learners have prior understanding of acids, bases, and neutralization reactions from previous classes.
Instructional Materials:
- Charts of laboratory setups for salt preparation
- Diagrams of sodium chloride electrolysis
- Samples of acidic, basic, and neutral salts
- Reaction equations and ionization data
Anticipation (Warm-Up) – 5 minutes
Begin with the question: “Why do some salts make water more acidic or basic?”
Introduce examples like ammonium chloride and sodium carbonate.
Building Knowledge (Main Lesson) – 25 minutes
- Acid-Base Properties of Salts
- Salts from strong acid + strong base = neutral (e.g., NaCl)
- Strong acid + weak base = acidic salt (e.g., NH₄Cl)
- Weak acid + strong base = basic salt (e.g., Na₂CO₃)
- Preparation of Salts
- Laboratory: Neutralization (acid + base), Precipitation, and Direct synthesis
- Industrial: Solvay process for Na₂CO₃, Haber process (indirect salt synthesis)
- Chemicals from Sodium Chloride
- Electrolysis of brine produces Cl₂, H₂, and NaOH
- Key industrial process for bleach and caustic soda
- Hydrolysis of Salts
- Salt ions react with water to affect pH
- Demonstrate using NH₄Cl (acidic) and NaCH₃COO (basic)
- Lewis Acids and Bases
- Lewis acid: electron pair acceptor; Lewis base: electron pair donor
- Examples: BF₃ (acid), NH₃ (base)
Learners’ Activities:
- Classify salts based on their parent acid/base strength
- Observe reactions and write net ionic equations
- Label Lewis acids and bases in sample reactions
Consolidation (Review and Assessment) – 10 minutes
- Oral Q&A on salt hydrolysis
- Class discussion: role of NaCl in industry
Homework / Assignment:
- List three acidic salts and three basic salts and write their parent reactions
- Draw the Lewis structure for a pair of Lewis acid-base reactions
- Research one industrial use of NaOH or Cl₂ from salt electrolysis
Notes – Detailed and Explains Acid-Base Properties of Salts are determined by the strengths of the acids and bases from which they originate. Salts affect the pH of aqueous solutions depending on whether their ions hydrolyze water.
Salt Preparation in labs involves simple reactions: acid + base → salt + water; while industrial methods involve large-scale synthesis and purification.
Sodium Chloride Electrolysis (brine) is a key industrial process yielding chlorine (for disinfectants), hydrogen (for ammonia synthesis), and sodium hydroxide (for soaps).
Hydrolysis involves reaction of ions with water, altering the solution’s pH: NH₄⁺ hydrolyzes to produce H⁺, making the solution acidic.
Lewis Theory classifies acids and bases based on electron pairs, not protons. This expands the scope to reactions not covered by Arrhenius or Bronsted-Lowry theories.
Expanded Notes / Instructions:
- Reinforce the link between hydrolysis and real-life pH changes in solutions
- Emphasize practical applications of salt chemistry in water treatment and industry
- Use interactive models for Lewis theory to help with abstract thinking
Inclusive / Differentiation:
- Guided note templates for learners needing structure
- Partner/group activities for collaborative learning
- Challenge tasks involving industrial salt reactions
Teacher’s Reflection (Post-Lesson Questions):
- Did learners grasp the link between parent acid/base and salt pH?
- Were they able to explain salt hydrolysis clearly?
- Should I reteach Lewis theory using more examples?