ACIDS, BASES AND SALTS

Definition of Acids
Strength of Acids

By the end of the lesson, the learner should be able to:
- Define an acid in terms of hydrogen ions
-Investigate reactions of magnesium and zinc carbonate with different acids
-Write equations for reactions taking place
-Explain why magnesium strip should be cleaned

In groups, learners are guided to:
Class experiment: React cleaned magnesium strips with 2M HCl, 2M ethanoic acid, 2M H₂SO₄, 2M ethanedioic acid. Record observations in table. Repeat using zinc carbonate. Write chemical equations. Discuss hydrogen ion displacement and gas evolution.

Magnesium strips, zinc carbonate, 2M HCl, 2M ethanoic acid, 2M H₂SO₄, 2M ethanedioic acid, test tubes, test tube rack
2M HCl, 2M ethanoic acid, universal indicator, pH chart, electrical conductivity apparatus, milliammeter, carbon electrodes, beakers, wires

KLB Secondary Chemistry Form 4, Pages 1-3

ACIDS, BASES AND SALTS

Definition of Bases
Strength of Bases
Acid-Base Reactions
Effect of Solvent on Acids

By the end of the lesson, the learner should be able to:
- Define a base in terms of hydroxide ions
-Investigate effect of calcium hydroxide in water
-Test solutions with litmus paper
-Explain dissociation of bases in water
- Write equations for acid-base reactions
-Explain neutralization process
-Identify products of acid-base reactions
-Demonstrate formation of salt and water

In groups, learners are guided to:
Teacher demonstration: Place dry calcium hydroxide on dry red litmus paper. Dissolve calcium hydroxide in water, test with litmus paper and phenolphthalein. Discuss observations and write dissociation equation. Define bases in terms of OH⁻ ions.
Q/A: Review acid and base definitions. Demonstrate neutralization reactions: HCl + NaOH, H₂SO₄ + Ca(OH)₂, HNO₃ + KOH. Write molecular and ionic equations. Explain H⁺ + OH⁻ → H₂O. Discuss salt formation. Use indicators to show neutralization point.

Calcium hydroxide, red litmus paper, phenolphthalein indicator, distilled water, test tubes, spatula, evaporating dish
2M NaOH, 2M ammonia solution, universal indicator, pH chart, electrical conductivity apparatus, milliammeter, carbon electrodes
Various acids and bases from previous lessons, indicators, beakers, measuring cylinders, stirring rods
HCl gas, distilled water, methylbenzene, magnesium ribbon, calcium carbonate, litmus paper, test tubes, gas absorption apparatus

KLB Secondary Chemistry Form 4, Pages 5-6
KLB Secondary Chemistry Form 4, Pages 6-7

ACIDS, BASES AND SALTS

Effect of Solvent on Bases
Amphoteric Oxides and Hydroxides

By the end of the lesson, the learner should be able to:
- Investigate effect of polar and non-polar solvents on ammonia gas
-Compare ammonia behavior in water vs methylbenzene
-Explain formation of ammonium hydroxide
-Write equations for ammonia dissolution in water

In groups, learners are guided to:
Class experiment: Test dry ammonia with dry litmus. Dissolve ammonia in water and test with litmus. Dissolve ammonia in methylbenzene and test with litmus. Record observations in table. Write equation for NH₃ + H₂O reaction. Explain why only aqueous ammonia shows basic properties.

Dry ammonia gas, distilled water, methylbenzene, red litmus paper, test tubes, gas collection apparatus
Al₂O₃, ZnO, PbO, Zn(OH)₂, Al(OH)₃, Pb(OH)₂, 2M HNO₃, 2M NaOH, boiling tubes, heating source

KLB Secondary Chemistry Form 4, Pages 9-10

ACIDS, BASES AND SALTS

Definition of Salts and Precipitation

By the end of the lesson, the learner should be able to:
- Define a salt as an ionic compound
-Define a precipitate
-Investigate precipitation reactions
-Write ionic equations showing formation of precipitates

In groups, learners are guided to:
Q/A: Review salt definition from Book 2. Demonstrate precipitation: Add sodium carbonate to solutions containing Mg²⁺, Ca²⁺, Zn²⁺, Al³⁺, Cu²⁺, Fe²⁺, Ba²⁺, Pb²⁺ ions. Record observations. Write ionic equations for precipitate formation. Explain why Fe³⁺ and Al³⁺ give different results.

Na₂CO₃ solution, salt solutions containing various metal ions, test tubes, droppers

KLB Secondary Chemistry Form 4, Pages 11-14

ACIDS, BASES AND SALTS

Solubility of Chlorides, Sulphates and Sulphites

By the end of the lesson, the learner should be able to:
- Find out cations that form insoluble chlorides, sulphates and sulphites
-Write ionic equations for formation of insoluble salts
-Distinguish between sulphate and sulphite precipitates
-Investigate effect of warming on precipitates

In groups, learners are guided to:
Class experiment: Add NaCl, Na₂SO₄, Na₂SO₃ to solutions of Pb²⁺, Ba²⁺, Mg²⁺, Ca²⁺, Zn²⁺, Cu²⁺, Fe²⁺, Fe³⁺, Al³⁺. Warm mixtures. Record observations in table. Test sulphite precipitates with dilute HCl. List soluble and insoluble salts.

2M NaCl, 2M Na₂SO₄, 2M Na₂SO₃, 0.1M salt solutions, dilute HCl, test tubes, heating source

KLB Secondary Chemistry Form 4, Pages 14-16

ACIDS, BASES AND SALTS

Complex Ions Formation
Solubility and Saturated Solutions

By the end of the lesson, the learner should be able to:
- Explain formation of complex ions
-Investigate reactions with excess sodium hydroxide and ammonia
-Identify metal ions that form complex ions
-Write equations for complex ion formation
- Define the term solubility
-Determine solubility of a given salt at room temperature
-Calculate mass of solute and solvent
-Express solubility in different units

In groups, learners are guided to:
Class experiment: Add NaOH dropwise then in excess to Mg²⁺, Ca²⁺, Zn²⁺, Al³⁺, Cu²⁺, Fe²⁺, Fe³⁺, Pb²⁺ solutions. Repeat with NH₃ solution. Record observations showing precipitate formation and dissolution. Write equations for complex ion formation: [Zn(OH)₄]²⁻, [Al(OH)₄]⁻, [Pb(OH)₄]²⁻, [Zn(NH₃)₄]²⁺, [Cu(NH₃)₄]²⁺.
Class experiment: Weigh evaporating dish and watch glass. Measure 20cm³ saturated KNO₃ solution. Record temperature. Evaporate to dryness carefully. Calculate masses of solute, solvent, and solution. Determine solubility per 100g water and in moles per litre. Discuss definition and significance.

2M NaOH, 2M NH₃ solution, 0.5M salt solutions, test tubes, droppers
Saturated KNO₃ solution, evaporating dish, watch glass, measuring cylinder, thermometer, balance, heating source

KLB Secondary Chemistry Form 4, Pages 15-16
KLB Secondary Chemistry Form 4, Pages 16-18

ACIDS, BASES AND SALTS

Effect of Temperature on Solubility

By the end of the lesson, the learner should be able to:
- Investigate the effect of temperature on solubility of potassium chlorate
-Record temperature at which crystals appear
-Calculate solubility at different temperatures
-Plot solubility curve

In groups, learners are guided to:
Class experiment: Dissolve 4g KClO₃ in 15cm³ water by warming. Cool while stirring and note crystallization temperature. Add 5cm³ water portions and repeat until total volume is 40cm³. Calculate solubility in g/100g water for each temperature. Plot solubility vs temperature graph.

KClO₃, measuring cylinders, thermometer, burette, boiling tubes, heating source, graph paper

KLB Secondary Chemistry Form 4, Pages 18-20

ACIDS, BASES AND SALTS

Solubility Curves and Applications

By the end of the lesson, the learner should be able to:
- Plot solubility curves for various salts
-Use solubility curves to determine mass of crystals formed
-Apply solubility curves to practical problems
-Compare solubility patterns of different salts

In groups, learners are guided to:
Using data from textbook, plot solubility curves for KNO₃, KClO₃, NaCl, CaSO₄. Calculate mass of crystals deposited when saturated solutions are cooled. Work through examples: KClO₃ cooled from 70°C to 30°C. Discuss applications in salt extraction and purification.

Graph paper, ruler, pencil, calculator, data tables from textbook

KLB Secondary Chemistry Form 4, Pages 20-21

ACIDS, BASES AND SALTS

Fractional Crystallization

By the end of the lesson, the learner should be able to:
- Define fractional crystallization
-Apply knowledge of solubility curves in separation of salts
-Calculate masses of salts that crystallize
-Explain separation of salt mixtures

In groups, learners are guided to:
Work through separation problems using solubility data for KNO₃ and KClO₃ mixtures. Calculate which salt crystallizes first when cooled from 50°C to 20°C. Plot combined solubility curves. Discuss applications in Lake Magadi and Ngomeni salt works. Solve practice problems.

Calculator, graph paper, data tables, worked examples from textbook

KLB Secondary Chemistry Form 4, Pages 21-22

ACIDS, BASES AND SALTS

Hardness of Water - Investigation
Types and Causes of Water Hardness

By the end of the lesson, the learner should be able to:
- Determine the effects of various salt solutions on soap
-Identify cations that cause hardness
-Distinguish between hard and soft water
-Investigate effect of boiling on water hardness
- Define temporary and permanent hardness
-Explain causes of temporary hardness
-Explain causes of permanent hardness
-Write equations for decomposition of hydrogen carbonates

In groups, learners are guided to:
Class experiment: Test soap lathering with distilled water, tap water, rainwater, and solutions of MgCl₂, NaCl, Ca(NO₃)₂, CaHCO₃, NaHCO₃, ZnSO₄. Record volumes of soap needed. Boil some solutions and retest. Compare results and identify hardness-causing ions.
Q/A: Review previous experiment results. Explain temporary hardness caused by Ca(HCO₃)₂ and Mg(HCO₃)₂. Write decomposition equations when boiled. Explain permanent hardness caused by CaSO₄, MgSO₄, Ca(NO₃)₂, Mg(NO₃)₂. Discuss why permanent hardness cannot be removed by boiling.

Soap solution, burette, various salt solutions, conical flasks, distilled water, tap water, rainwater, heating source
Student books, examples from previous experiment, chalkboard for equations

KLB Secondary Chemistry Form 4, Pages 22-24
KLB Secondary Chemistry Form 4, Pages 24-25

ACIDS, BASES AND SALTS

Effects of Hard Water

By the end of the lesson, the learner should be able to:
- State disadvantages of hard water
-State advantages of hard water
-Explain formation of scum and fur
-Discuss economic and health implications

In groups, learners are guided to:
Discussion based on practical experience: Soap wastage, scum formation on clothes, fur in kettles and pipes, pipe bursting in boilers. Advantages: calcium for bones, protection of lead pipes, use in brewing. Show examples of fur deposits. Calculate economic costs of hard water in households.

Samples of fur deposits, pictures of scaled pipes, calculator for cost analysis

KLB Secondary Chemistry Form 4, Pages 24-25

ACIDS, BASES AND SALTS

Effects of Hard Water

By the end of the lesson, the learner should be able to:
- State disadvantages of hard water
-State advantages of hard water
-Explain formation of scum and fur
-Discuss economic and health implications

In groups, learners are guided to:
Discussion based on practical experience: Soap wastage, scum formation on clothes, fur in kettles and pipes, pipe bursting in boilers. Advantages: calcium for bones, protection of lead pipes, use in brewing. Show examples of fur deposits. Calculate economic costs of hard water in households.

Samples of fur deposits, pictures of scaled pipes, calculator for cost analysis

KLB Secondary Chemistry Form 4, Pages 24-25

ACIDS, BASES AND SALTS

Methods of Removing Hardness I

By the end of the lesson, the learner should be able to:
- Explain removal of hardness by boiling
-Explain removal by distillation
-Write equations for these processes
-Compare effectiveness of different methods

In groups, learners are guided to:
Demonstrate boiling method: Boil hard water samples from previous experiments and test with soap. Write equations for Ca(HCO₃)₂ and Mg(HCO₃)₂ decomposition. Discuss distillation method using apparatus setup. Compare costs and effectiveness. Explain why boiling only removes temporary hardness.

Hard water samples, heating source, soap solution, distillation apparatus diagram

KLB Secondary Chemistry Form 4, Pages 25-26

ACIDS, BASES AND SALTS
METALS

Methods of Removing Hardness II
Chemical Properties I - Reaction with Air
Chemical Properties II - Reaction with Water

By the end of the lesson, the learner should be able to:
- Explain removal using sodium carbonate
-Describe ion exchange method
-Explain removal using calcium hydroxide and ammonia
-Write equations for all processes
Test metal reactions with cold water and steam
- Arrange metals by reactivity
- Explain aluminium's apparent unreactivity
- Write chemical equations for reactions

In groups, learners are guided to:
Demonstrate addition of Na₂CO₃ to hard water - observe precipitation. Explain ion exchange using resin (NaX) showing Ca²⁺ + 2NaX → CaX₂ + 2Na⁺. Discuss regeneration with brine. Write equations for Ca(OH)₂ and NH₃ methods. Compare all methods for effectiveness and cost.
Experiment 5.2: Test metals with cold water and steam
- Use Table 5.4 for observations
- Test solutions with indicators
- Arrange metals in reactivity order

Na₂CO₃ solution, hard water samples, ion exchange resin diagram, Ca(OH)₂, NH₃ solution
Deflagrating spoons, metal samples (Na, Al, Zn, Fe, Cu), Bunsen burners, safety equipment
Metal samples, cold water, steam generator, test tubes, universal indicator, safety equipment

KLB Secondary Chemistry Form 4, Pages 25-26
KLB Secondary Chemistry Form 4, Pages 154-156

METALS

Chemical Properties III - Reaction with Chlorine

By the end of the lesson, the learner should be able to:
Investigate metal reactions with chlorine gas
- Write equations for chloride formation
- Compare reaction vigor
- Observe product characteristics

In groups, learners are guided to:
Experiment 5.3: React hot metals with chlorine gas (FUME CUPBOARD)
- Observe color changes and fume formation
- Record all observations
- Write balanced equations

Chlorine gas, gas jars, metal samples, tongs, deflagrating spoons, fume cupboard, safety equipment

KLB Secondary Chemistry Form 4, Pages 156-157

METALS

Chemical Properties IV - Reaction with Acids

By the end of the lesson, the learner should be able to:
Test metal reactions with dilute and concentrated acids
- Compare reaction patterns
- Write chemical equations
- Explain passivation effects

In groups, learners are guided to:
Experiment 5.4: Test metals with various acids - HCl, HNO₃, H₂SO₄
- Use Table 5.5 for systematic recording
- Observe gas evolution
- Discuss passivation

Various acids (dilute and concentrated), metal strips, test tubes, gas collection apparatus, safety equipment

KLB Secondary Chemistry Form 4, Pages 157-158

METALS

Uses of Metals I - Sodium and Aluminium

By the end of the lesson, the learner should be able to:
State uses of sodium and its compounds
- Explain aluminium applications
- Relate properties to uses
- Describe alloy formation and uses

In groups, learners are guided to:
Discussion on sodium uses in industry
- Aluminium applications in transport and construction
- Study duralumin and other alloys
- Property-use relationships

Charts showing metal applications, alloy samples, aircraft parts, cooking vessels

KLB Secondary Chemistry Form 4, Pages 158-159

METALS

Uses of Metals I - Sodium and Aluminium
Uses of Metals II - Zinc, Copper and Iron

By the end of the lesson, the learner should be able to:
State uses of sodium and its compounds
- Explain aluminium applications
- Relate properties to uses
- Describe alloy formation and uses
Explain galvanization process
- Describe copper electrical applications
- Compare iron, steel, and cast iron uses
- Analyze alloy compositions and properties

In groups, learners are guided to:
Discussion on sodium uses in industry
- Aluminium applications in transport and construction
- Study duralumin and other alloys
- Property-use relationships
Study galvanization and rust prevention
- Copper in electrical applications
- Different types of steel and their compositions
- Alloy property comparisons

Charts showing metal applications, alloy samples, aircraft parts, cooking vessels
Galvanized sheets, copper wires, steel samples, alloy composition charts, brass and bronze samples

KLB Secondary Chemistry Form 4, Pages 158-159
KLB Secondary Chemistry Form 4, Pages 159-161

METALS

Steel Types and Alloys

By the end of the lesson, the learner should be able to:
Compare cast iron, wrought iron, and steel
- Analyze different steel compositions
- Explain alloy property enhancement
- Describe specialized steel applications

In groups, learners are guided to:
Study cast iron, wrought iron, mild steel, and stainless steel
- Analyze carbon content effects
- Specialized steels for tools and instruments
- Discussion on alloy design

Steel samples with different compositions, carbon content charts, specialized tools, stainless steel items

KLB Secondary Chemistry Form 4, Pages 159-161

METALS
RADIOACTIVITY

Environmental Effects of Metal Extraction
Introduction, Nuclear Stability and Types of Radioactivity

By the end of the lesson, the learner should be able to:
Identify environmental impacts of mining
- Explain pollution from metal extraction
- Describe waste management strategies
- Discuss NEMA regulations in Kenya

In groups, learners are guided to:
Analysis of mining environmental impact
- Air, water, and land pollution from extraction
- Waste management and slag utilization
- NEMA role and regulations

Environmental impact case studies, pollution images, NEMA regulation documents, waste management examples
Periodic table, atomic structure charts, Table 7.1, nuclear stability diagrams

KLB Secondary Chemistry Form 4, Pages 161-162

RADIOACTIVITY

Types of Radiation and Their Properties
Radioactive Decay and Half-Life Concept

By the end of the lesson, the learner should be able to:
Identify alpha, beta, and gamma radiations
- Compare penetrating abilities and ionizing power
- Explain electric field deflection
- Analyze safety implications

In groups, learners are guided to:
Study alpha (α), beta (β), gamma (γ) characteristics
- Figure 7.2 - penetrating power demonstration
- Figure 7.3 - electric field effects
- Discussion on radiation protection and detection

Radiation type charts, penetration diagrams, electric field illustrations, safety equipment charts
Graph paper, Table 7.2 data, calculators, decay curve examples, half-life data table

KLB Secondary Chemistry Form 4, Pages 201-204

RADIOACTIVITY

Half-Life Calculations and Problem Solving
Nuclear Reactions and Equations
Radioactive Decay Series and Sequential Reactions

By the end of the lesson, the learner should be able to:
Solve complex half-life problems
- Determine original amounts from remaining masses
- Apply step-by-step and formula methods
- Compare isotope decay rates
Explain sequential radioactive decay
- Trace decay series pathways
- Identify stable end products
- Complete partial decay series

In groups, learners are guided to:
Worked examples on half-life calculations using both methods
- Practice determining original amounts
- Study various isotope half-lives
- Comprehensive problem-solving sessions
Study thorium-232 decay series example
- Trace sequential alpha and beta emissions
- Identify stable lead-208 endpoint
- Practice completing decay series with missing nuclides

Calculators, comprehensive problem sets, worked examples, isotope half-life comparison tables
Nuclear equation examples, periodic table, conservation law charts, practice worksheets
Decay series charts, thorium series diagram, nuclide stability charts, practice decay series

KLB Secondary Chemistry Form 4, Pages 204-206
KLB Secondary Chemistry Form 4, Pages 206-207

RADIOACTIVITY

Nuclear Fission and Chain Reactions
Nuclear Fusion and Energy Comparisons

By the end of the lesson, the learner should be able to:
Define nuclear fission process
- Explain mechanism of chain reactions
- Calculate energy release from mass defect
- Describe controlled vs uncontrolled fission

In groups, learners are guided to:
Study uranium-235 fission example
- Chain reaction mechanism and critical mass
- Energy calculation from mass-energy equivalence
- Nuclear reactor vs atomic bomb principles

Fission reaction diagrams, chain reaction illustrations, nuclear reactor diagrams, energy calculation examples
Fusion reaction diagrams, comparison tables, stellar fusion charts, energy comparison data

KLB Secondary Chemistry Form 4, Pages 207-208

RADIOACTIVITY

Medical and Diagnostic Applications

By the end of the lesson, the learner should be able to:
Describe medical applications of radioisotopes
- Explain cancer treatment using radiation
- Discuss diagnostic procedures and imaging
- Analyze therapeutic vs diagnostic uses

In groups, learners are guided to:
Study cobalt-60 and caesium-137 in cancer treatment
- Iodine-131 in thyroid monitoring
- Bone growth and fracture healing monitoring
- Sterilization of surgical instruments

Medical radioisotope charts, treatment procedure diagrams, diagnostic equipment images, case studies

KLB Secondary Chemistry Form 4, Pages 208-209

RADIOACTIVITY

Industrial, Agricultural and Dating Applications

By the end of the lesson, the learner should be able to:
Explain industrial leak detection
- Describe agricultural monitoring techniques
- Discuss carbon-14 dating principles
- Analyze food preservation methods

In groups, learners are guided to:
Study leak detection using short half-life isotopes
- Carbon-14 dating of archaeological materials
- Phosphorus tracking in agriculture
- Gamma radiation food preservation

Carbon dating examples, agricultural application charts, industrial use diagrams, food preservation data

KLB Secondary Chemistry Form 4, Pages 208-209

RADIOACTIVITY

Radiation Hazards and Environmental Impact
Safety Measures and International Control

By the end of the lesson, the learner should be able to:
Identify radiation health hazards
- Explain genetic mutation effects
- Discuss major nuclear accidents
- Analyze long-term environmental contamination
Explain radiation protection principles
- Describe proper storage and disposal methods
- Discuss IAEA role and standards
- Analyze monitoring and control systems

In groups, learners are guided to:
Study Chernobyl and Three Mile Island accidents
- Genetic mutation and cancer effects
- Long-term radiation exposure consequences
- Nuclear waste disposal challenges
Study IAEA guidelines and international cooperation
- Radiation protection protocols and ALARA principle
- Safe storage, transport and disposal methods
- Environmental monitoring systems

Accident case studies, environmental impact data, radiation exposure charts, contamination maps
IAEA guidelines, safety protocol charts, monitoring equipment diagrams, international cooperation data

KLB Secondary Chemistry Form 4, Pages 209-210

RADIOACTIVITY

Half-Life Problem Solving and Graph Analysis

By the end of the lesson, the learner should be able to:
Solve comprehensive half-life problems
- Analyze experimental decay data
- Plot and interpret decay curves
- Determine half-lives graphically

In groups, learners are guided to:
Plot decay curves from experimental data
- Determine half-lives from graphs
- Analyze count rate vs time data
- Complex half-life calculation problems

Graph paper, experimental data sets, calculators, statistical analysis examples, comprehensive problem sets

KLB Secondary Chemistry Form 4, Pages 199-210

RADIOACTIVITY

Nuclear Equations and Conservation Laws

By the end of the lesson, the learner should be able to:
Balance complex nuclear equations
- Complete nuclear reaction series
- Identify unknown nuclides using conservation laws
- Apply mass-energy relationships

In groups, learners are guided to:
Practice balancing nuclear reactions with multiple steps
- Complete partial decay series
- Identify missing nuclides using conservation principles
- Mass-energy calculation problems

Nuclear equation worksheets, periodic table, decay series diagrams, conservation law examples

KLB Secondary Chemistry Form 4, Pages 199-210