ACIDS, BASES AND SALTS

Definition 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

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

KLB Secondary Chemistry Form 4, Pages 1-3

ACIDS, BASES AND SALTS

Strength of Acids
Definition of Bases

By the end of the lesson, the learner should be able to:
- Compare strengths of acids using pH values
-Determine strengths of acids by comparing their electrical conductivity
-Classify acids as either strong or weak
-Explain complete and partial dissociation of acids

Class experiment: Test pH of 2M HCl and 2M ethanoic acid using universal indicator. Set up electrical conductivity apparatus with both acids. Record milliammeter readings. Compare results and explain in terms of hydrogen ion concentration. Discuss strong vs weak acid definitions.

2M HCl, 2M ethanoic acid, universal indicator, pH chart, electrical conductivity apparatus, milliammeter, carbon electrodes, beakers, wires
Calcium hydroxide, red litmus paper, phenolphthalein indicator, distilled water, test tubes, spatula, evaporating dish

KLB Secondary Chemistry Form 4, Pages 3-5

ACIDS, BASES AND SALTS

Strength of Bases
Acid-Base Reactions

By the end of the lesson, the learner should be able to:
- Compare strengths of bases using pH values
-Determine strengths of bases by comparing their electrical conductivity
-Classify bases as either strong or weak
-Explain complete and partial ionization of bases

Class experiment: Test pH of 2M NaOH and 2M ammonia solution using universal indicator. Test electrical conductivity of both solutions using same apparatus as acids. Compare deflections and pH values. Explain in terms of OH⁻ ion concentration and complete vs partial ionization.

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

KLB Secondary Chemistry Form 4, Pages 5-7

ACIDS, BASES AND SALTS

Effect of Solvent on Acids
Effect of Solvent on Bases

By the end of the lesson, the learner should be able to:
- Explain effect of polar and non-polar solvents on hydrogen chloride
-Investigate HCl behavior in water vs methylbenzene
-Define polar and non-polar solvents
-Explain why acids show properties only in polar solvents

Teacher demonstration: Dissolve HCl gas in water and methylbenzene separately. Test both solutions with litmus paper, magnesium, and calcium carbonate. Compare observations. Explain polarity of water vs methylbenzene. Discuss dissociation vs molecular solution.

HCl gas, distilled water, methylbenzene, magnesium ribbon, calcium carbonate, litmus paper, test tubes, gas absorption apparatus
Dry ammonia gas, distilled water, methylbenzene, red litmus paper, test tubes, gas collection apparatus

KLB Secondary Chemistry Form 4, Pages 7-9

ACIDS, BASES AND SALTS

Amphoteric Oxides and Hydroxides
Definition of Salts and Precipitation

By the end of the lesson, the learner should be able to:
- Define amphoteric oxides
-Identify some amphoteric oxides
-Investigate reactions with both acids and alkalis
-Write equations for amphoteric behavior

Class experiment: React Al₂O₃, ZnO, PbO, Zn(OH)₂, Al(OH)₃, Pb(OH)₂ with 2M HNO₃ and 2M NaOH. Warm mixtures. Record observations in table. Write equations showing basic and acidic behavior. Discuss dual nature of amphoteric substances.

Al₂O₃, ZnO, PbO, Zn(OH)₂, Al(OH)₃, Pb(OH)₂, 2M HNO₃, 2M NaOH, boiling tubes, heating source
Na₂CO₃ solution, salt solutions containing various metal ions, test tubes, droppers

KLB Secondary Chemistry Form 4, Pages 10-11

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

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

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

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⁺.

2M NaOH, 2M NH₃ solution, 0.5M salt solutions, test tubes, droppers

KLB Secondary Chemistry Form 4, Pages 15-16

ACIDS, BASES AND SALTS

Solubility and Saturated Solutions

By the end of the lesson, the learner should be able to:
- Define the term solubility
-Determine solubility of a given salt at room temperature
-Calculate mass of solute and solvent
-Express solubility in different units

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.

Saturated KNO₃ solution, evaporating dish, watch glass, measuring cylinder, thermometer, balance, heating source

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

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
Fractional Crystallization

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

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

KLB Secondary Chemistry Form 4, Pages 20-21

ACIDS, BASES AND SALTS

Hardness of Water - Investigation

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

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.

Soap solution, burette, various salt solutions, conical flasks, distilled water, tap water, rainwater, heating source

KLB Secondary Chemistry Form 4, Pages 22-24

ACIDS, BASES AND SALTS

Types and Causes of Water Hardness

By the end of the lesson, the learner should be able to:
- Define temporary and permanent hardness
-Explain causes of temporary hardness
-Explain causes of permanent hardness
-Write equations for decomposition of hydrogen carbonates

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.

Student books, examples from previous experiment, chalkboard for equations

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

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

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
SULPHUR AND ITS COMPOUNDS

Methods of Removing Hardness II
Extraction of Sulphur

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

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.

Na₂CO₃ solution, hard water samples, ion exchange resin diagram, Ca(OH)₂, NH₃ solution
Charts showing periodic table, Diagram of Frasch process, Samples of sulphur compounds (pyrites, gypsum)

KLB Secondary Chemistry Form 4, Pages 25-26

SULPHUR AND ITS COMPOUNDS

Allotropes of Sulphur
Physical Properties of Sulphur - Solubility

By the end of the lesson, the learner should be able to:
Define allotropy and allotropes. Prepare rhombic sulphur in the laboratory. Prepare monoclinic sulphur in the laboratory. Compare the properties of rhombic and monoclinic sulphur.

Practical work: Experiment 1(a) - Preparation of rhombic sulphur using carbon(IV) sulphide. Practical work: Experiment 1(b) - Preparation of monoclinic sulphur by heating and cooling. Observation: Using hand lens to examine crystal shapes. Discussion: Compare crystal structures and transition temperature.

Powdered sulphur, Carbon(IV) sulphide, Evaporating dish, Glass rod, Hand lens, Boiling tubes, Filter paper, Beakers
Powdered sulphur, Water, Benzene, Methylbenzene, Carbon(IV) sulphide, Test tubes, Charts showing molecular structure

KLB Secondary Chemistry Form 4, Pages 161-163

SULPHUR AND ITS COMPOUNDS

Physical Properties of Sulphur - Effect of Heat
Chemical Properties of Sulphur - Reactions with Elements

By the end of the lesson, the learner should be able to:
Investigate the effect of heat on sulphur. Describe changes in color and viscosity of molten sulphur. Explain the molecular changes occurring during heating. Identify "flowers of sulphur".

Practical work: Experiment 2(b) - Heating sulphur and observing changes. Observation: Color changes from yellow to amber to reddish-brown to black. Testing viscosity by inverting test tube. Demonstration: Sublimation of sulphur vapour. Discussion: Breaking of S8 rings to form long chains.

Powdered sulphur, Test tubes, Bunsen burner, Cold surface for condensation, Thermometer, Safety equipment
Sulphur, Iron powder, Copper powder, Oxygen gas jar, Deflagrating spoon, Moist litmus papers, Test tubes, Bunsen burner

KLB Secondary Chemistry Form 4, Pages 164-165

SULPHUR AND ITS COMPOUNDS

Chemical Properties of Sulphur - Reactions with Acids
Uses of Sulphur and Introduction to Oxides

By the end of the lesson, the learner should be able to:
Investigate the reaction of sulphur with concentrated acids. Identify the products formed in these reactions. Write balanced equations for oxidation reactions. Test for sulphate ions using barium chloride.

Practical work: Experiment 3(b) - Reactions with concentrated nitric(V) acid, sulphuric(VI) acid, and hydrochloric acid. Testing with barium chloride solution. Observation: Formation of sulphate ions, brown fumes, no reaction with HCl. Discussion: Sulphur as a reducing agent, acids as oxidizing agents.

Sulphur powder, Concentrated HNO3, Concentrated H2SO4, Concentrated HCl, Barium chloride solution, Test tubes, Fume cupboard access
Charts showing uses of sulphur, Samples of vulcanized rubber, Fungicides, Industrial photographs, Textbook diagrams

KLB Secondary Chemistry Form 4, Pages 167-168

SULPHUR AND ITS COMPOUNDS

Preparation of Sulphur(IV) Oxide
Physical and Chemical Properties of Sulphur(IV) Oxide

By the end of the lesson, the learner should be able to:
Describe laboratory preparation of sulphur(IV) oxide. Set up apparatus for gas preparation and collection. Write balanced equations for the preparation reactions. Explain the drying and collection methods used.

Practical work: Experiment 4 - Preparation of SO2 using sodium sulphite and dilute HCl. Apparatus setup: Round-bottomed flask, delivery tube, gas jars. Collection: Downward delivery method. Testing: Using acidified potassium chromate(VI) paper. Alternative method: Copper + concentrated H2SO

Sodium sulphite, Dilute HCl, Round-bottomed flask, Delivery tubes, Gas jars, Concentrated H2SO4 for drying, Acidified potassium chromate(VI) paper
SO2 gas from previous preparation, Litmus papers, Universal indicator, 0.1M NaOH solution, Water, Test tubes, Safety equipment

KLB Secondary Chemistry Form 4, Pages 170-171

SULPHUR AND ITS COMPOUNDS

Bleaching Action of Sulphur(IV) Oxide

By the end of the lesson, the learner should be able to:
Investigate the bleaching properties of SO Compare SO2 bleaching with chlorine bleaching. Explain the mechanism of SO2 bleaching. Relate bleaching to paper manufacturing.

Practical work: Experiment 6 - Placing colored flower petals in SO2 gas. Observation: Temporary bleaching effect. Discussion: SO2 + H2O → H2SO3, reduction of organic dyes. Comparison: Permanent vs temporary bleaching. Application: Paper industry bleaching processes.

Colored flower petals (red/blue), SO2 gas jars, Hand lens for observation, Charts comparing bleaching agents

KLB Secondary Chemistry Form 4, Pages 173

SULPHUR AND ITS COMPOUNDS

Reducing Action of Sulphur(IV) Oxide

By the end of the lesson, the learner should be able to:
Investigate SO2 as a reducing agent. Test reactions with various oxidizing agents. Write ionic equations for redox reactions. Identify color changes in redox reactions.

Practical work: Experiment 7 - Testing SO2 with acidified potassium dichromate(VI), potassium manganate(VII), bromine water, iron(III) chloride. Recording observations in Table 6. Color changes: Orange to green, purple to colorless, brown to colorless, yellow to pale green. Writing half-equations and overall equations.

SO2 gas, Acidified K2Cr2O7, Acidified KMnO4, Bromine water, Iron(III) chloride solution, Concentrated HNO3, Test tubes

KLB Secondary Chemistry Form 4, Pages 173-176

SULPHUR AND ITS COMPOUNDS

Oxidising Action of Sulphur(IV) Oxide

By the end of the lesson, the learner should be able to:
Investigate SO2 as an oxidizing agent. Demonstrate reaction with stronger reducing agents. Explain the dual nature of SO Write equations for oxidation reactions by SO

Practical work: Experiment 8 - Lowering burning magnesium into SO2 gas. Observation: Continued burning, white fumes of MgO, yellow specks of sulphur. Reaction with hydrogen sulphide gas (demonstration). Discussion: SO2 decomposition providing oxygen. Writing equations: 2Mg + SO2 → 2MgO + S.

SO2 gas jars, Magnesium ribbon, Deflagrating spoon, Hydrogen sulphide gas, Water droppers, Safety equipment

KLB Secondary Chemistry Form 4, Pages 176-177

SULPHUR AND ITS COMPOUNDS

Test for Sulphate and Sulphite Ions & Uses of SO2
Large-scale Manufacture of Sulphuric(VI) Acid - Contact Process

By the end of the lesson, the learner should be able to:
Carry out confirmatory tests for sulphate and sulphite ions. Distinguish between sulphate and sulphite using chemical tests. List the uses of sulphur(IV) oxide. Explain the applications in industry.

Practical work: Experiment 9 - Testing sodium sulphate and sodium sulphite with barium chloride. Adding dilute HCl to precipitates. Recording observations in Table 8. Discussion: BaSO4 insoluble in acid, BaSO3 dissolves. Uses: Raw material for H2SO4, bleaching wood pulp, fumigant, preservative.

Sodium sulphate solution, Sodium sulphite solution, Barium chloride solution, Dilute HCl, Test tubes, Charts showing industrial uses
Flow chart diagrams, Charts showing industrial plant, Samples of catalyst (V2O5), Photographs of Thika chemical plant, Calculator for percentage calculations

KLB Secondary Chemistry Form 4, Pages 178-179

SULPHUR AND ITS COMPOUNDS

Properties of Concentrated Sulphuric(VI) Acid - Dehydrating Properties

By the end of the lesson, the learner should be able to:
Investigate the dehydrating properties of concentrated H2SO Demonstrate removal of water from hydrated salts. Show dehydration of organic compounds. Explain the hygroscopic nature of the acid.

Practical work: Experiment 10 - Adding concentrated H2SO4 to copper(II) sulphate crystals, sucrose crystals, ethanol. Observations: Blue to white crystals, charring of sugar, formation of ethene. Safety: Proper dilution technique - acid to water. Testing evolved gases. Discussion: Chemical vs physical dehydration.

Concentrated H2SO4, Copper(II) sulphate crystals, Sucrose, Ethanol, KMnO4 solution, Test tubes, Beakers, Safety equipment, Fume cupboard

KLB Secondary Chemistry Form 4, Pages 181-183

SULPHUR AND ITS COMPOUNDS

Properties of Concentrated Sulphuric(VI) Acid - Oxidizing Properties

By the end of the lesson, the learner should be able to:
Investigate the oxidizing properties of concentrated H2SO Test reactions with metals and non-metals. Identify the products of oxidation reactions. Write balanced equations for redox reactions.

Practical work: Experiment 10 (continued) - Reactions with copper foil, zinc granules, charcoal. Testing evolved gases with acidified K2Cr2O7 paper, lime water. Observations: SO2 evolution, color changes. Discussion: H2SO4 → SO2 + H2O + [O]. Writing half-equations and overall equations.

Copper foil, Zinc granules, Charcoal powder, Concentrated H2SO4, Acidified K2Cr2O7 paper, Lime water, Test tubes, Bunsen burner

KLB Secondary Chemistry Form 4, Pages 183-184

SULPHUR AND ITS COMPOUNDS

Properties of Concentrated Sulphuric(VI) Acid - Displacement Reactions

By the end of the lesson, the learner should be able to:
Investigate acid displacement reactions. Demonstrate formation of volatile acids. Test the evolved gases for identification. Write equations for displacement reactions.

Practical work: Experiment 10 (continued) - Reactions with potassium nitrate and sodium chloride. Testing evolved gases with moist blue litmus, concentrated ammonia. Observations: Brown fumes (NO2), white fumes (HCl). Discussion: Less volatile acid displacing more volatile acids. Industrial applications.

Potassium nitrate crystals, Sodium chloride crystals, Concentrated H2SO4, Moist blue litmus paper, Concentrated ammonia, Test tubes, Bunsen burner

KLB Secondary Chemistry Form 4, Pages 184

SULPHUR AND ITS COMPOUNDS

Reactions of Dilute Sulphuric(VI) Acid - With Metals

By the end of the lesson, the learner should be able to:
Investigate reactions of dilute H2SO4 with metals. Compare reactivity of different metals. Test for hydrogen gas evolution. Relate reactions to reactivity series.

Practical work: Experiment 11 - Reactions with magnesium, zinc, copper. Testing evolved gas with burning splint. Recording observations in Table 10. Discussion: More reactive metals above hydrogen displace it. Vigour of reaction decreases down reactivity series. Writing ionic equations.

Magnesium ribbon, Zinc granules, Copper turnings, Dilute H2SO4, Test tubes, Burning splints, Reactivity series chart

KLB Secondary Chemistry Form 4, Pages 184-185

SULPHUR AND ITS COMPOUNDS

Reactions of Dilute Sulphuric(VI) Acid - With Carbonates

By the end of the lesson, the learner should be able to:
Investigate reactions of dilute H2SO4 with carbonates. Test for carbon dioxide evolution. Explain why some reactions stop prematurely. Compare reactions of different metal carbonates.

Practical work: Experiment 12 - Reactions with sodium carbonate, zinc carbonate, calcium carbonate, copper(II) carbonate. Testing evolved gas with lime water. Recording observations in Table 1 Discussion: Formation of insoluble calcium sulphate coating. Effervescence and CO2 identification.

Sodium carbonate, Zinc carbonate, Calcium carbonate, Copper(II) carbonate, Dilute H2SO4, Lime water, Test tubes

KLB Secondary Chemistry Form 4, Pages 185-186

SULPHUR AND ITS COMPOUNDS

Reactions of Dilute Sulphuric(VI) Acid - With Oxides and Hydroxides

By the end of the lesson, the learner should be able to:
Investigate reactions of dilute H2SO4 with metal oxides and hydroxides. Identify neutralization reactions. Explain formation of insoluble sulphates. Write equations for acid-base reactions.

Practical work: Experiment 13 - Reactions with magnesium oxide, zinc oxide, copper(II) oxide, lead(II) oxide, sodium hydroxide. Recording observations in Table 1 Discussion: Salt and water formation, immediate stopping with lead(II) oxide due to insoluble PbSO Acid-base neutralization concept.

Metal oxides (MgO, ZnO, CuO, PbO), NaOH solution, 2M H2SO4, Test tubes, Bunsen burner for warming

KLB Secondary Chemistry Form 4, Pages 186-187

SULPHUR AND ITS COMPOUNDS

Hydrogen Sulphide - Preparation and Physical Properties

By the end of the lesson, the learner should be able to:
Describe laboratory preparation of hydrogen sulphide. Set up apparatus for H2S preparation. State the physical properties of H2S. Explain the toxicity and safety precautions.

Demonstration: Figure 13 apparatus setup for H2S preparation. Reaction: FeS + 2HCl → FeCl2 + H2S. Collection over warm water due to solubility. Drying: Using anhydrous CaCl2 (not H2SO4). Properties: Colorless, rotten egg smell, poisonous, denser than air. Safety precautions in handling.

Iron(II) sulphide, Dilute HCl, Apparatus for gas generation, Anhydrous CaCl2, Gas jars, Safety equipment, Fume cupboard

KLB Secondary Chemistry Form 4, Pages 187-188

SULPHUR AND ITS COMPOUNDS

Chemical Properties of Hydrogen Sulphide

By the end of the lesson, the learner should be able to:
Investigate H2S as a reducing agent. Test reactions with oxidizing agents. Demonstrate precipitation of metal sulphides. Write ionic equations for redox reactions.

Practical demonstrations: H2S with bromine water, iron(III) chloride, acidified KMnO4, K2Cr2O7. Precipitation tests: H2S with copper(II) sulphate, lead(II) nitrate, zinc sulphate. Color changes: Brown to colorless, yellow to green, purple to colorless. Formation of black, yellow, and white precipitates.

H2S gas, Bromine water, Iron(III) chloride, KMnO4, K2Cr2O7, Metal salt solutions, Test tubes, Droppers

KLB Secondary Chemistry Form 4, Pages 188-190

SULPHUR AND ITS COMPOUNDS
CHLORINE AND ITS COMPOUNDS
CHLORINE AND ITS COMPOUNDS

Pollution Effects and Summary
Introduction and Preparation of Chlorine
Physical Properties of Chlorine

By the end of the lesson, the learner should be able to:
Explain environmental pollution by sulphur compounds. Describe formation and effects of acid rain. Suggest methods to reduce sulphur pollution. Summarize key concepts of sulphur chemistry.

Discussion: Sources of SO2 pollution - burning fossil fuels, metal extraction, H2SO4 manufacture. Formation of acid rain: SO2 + H2O → H2SO3 → H2SO Effects: Plant damage, aquatic life destruction, building corrosion, soil acidification. Control measures: Scrubbing with Ca(OH)2, catalytic converters. Revision: Key reactions, properties, uses.

Charts showing pollution effects, Photographs of acid rain damage, Environmental data, Summary charts of reactions, Industrial pollution control diagrams
Manganese(IV) oxide, Concentrated HCl, Gas collection apparatus, Water, Concentrated H2SO4, Blue litmus paper, Gas jars
Preserved chlorine gas, Water trough, Gas jars, Observation tables, Safety equipment

KLB Secondary Chemistry Form 4, Pages 190-194

CHLORINE AND ITS COMPOUNDS

Chemical Properties of Chlorine - Reaction with Water
Chemical Properties of Chlorine - Reaction with Metals

By the end of the lesson, the learner should be able to:
Investigate the reaction of chlorine with water. Explain the formation of chlorine water. Test the acidic nature of chlorine water. Demonstrate the bleaching action of chlorine.

Practical work: Experiment 6.3 - Bubbling chlorine through water. Testing with litmus papers (dry vs moist). Testing with colored flower petals. Formation of green-yellow chlorine water. Writing equations: Cl2 + H2O → HCl + HOCl. Discussion: Formation of hypochlorous acid and hydrochloric acid.

Chlorine gas, Distilled water, Blue and red litmus papers, Colored flower petals, Gas jars, Boiling tubes
Magnesium ribbon, Iron wire, Chlorine gas, Deflagrating spoon, Combustion tube, Anhydrous CaCl2, Gas jars

KLB Secondary Chemistry Form 4, Pages 197-199

CHLORINE AND ITS COMPOUNDS

Chemical Properties of Chlorine - Reaction with Non-metals
Oxidising Properties of Chlorine

By the end of the lesson, the learner should be able to:
Investigate reactions of chlorine with non-metals. Demonstrate reaction with phosphorus and hydrogen. Write equations for non-metal chloride formation. Explain the vigorous nature of these reactions.

Practical work: Experiment 6.5 - Warming red phosphorus and lowering into chlorine. Demonstration: Burning hydrogen jet in chlorine. Observations: White fumes of phosphorus chlorides, hydrogen chloride formation. Writing equations: P4 + 6Cl2 → 4PCl3, H2 + Cl2 → 2HCl. Discussion: Formation of covalent chlorides.

Red phosphorus, Hydrogen gas, Chlorine gas, Deflagrating spoon, Gas jars, Bunsen burner, Safety equipment
Sodium sulphite solution, Barium nitrate, Lead nitrate, Hydrogen sulphide gas, Aqueous ammonia, Chlorine gas, Test tubes

KLB Secondary Chemistry Form 4, Pages 201

CHLORINE AND ITS COMPOUNDS

Reaction of Chlorine with Alkali Solutions
Oxidising Properties - Displacement Reactions

By the end of the lesson, the learner should be able to:
Investigate reactions of chlorine with alkalis. Compare reactions with cold dilute and hot concentrated alkalis. Write equations for formation of chlorates and hypochlorites. Explain formation of bleaching powder.

Practical work: Experiment 6.7 - Bubbling chlorine through cold dilute NaOH and hot concentrated NaOH. Recording observations in Table 6. Formation of pale-yellow solution (cold) vs colorless solution (hot). Equations: 3Cl2 + 6NaOH → 5NaCl + NaClO3 + 3H2O (hot), Cl2 + 2NaOH → NaCl + NaClO + H2O (cold). Discussion: Industrial production of bleaching powder.

Sodium hydroxide solutions (dilute cold, concentrated hot), Chlorine gas, Beakers, Bunsen burner, Thermometer
Potassium bromide solution, Potassium iodide solution, Chlorine gas, Test tubes, Observation charts

KLB Secondary Chemistry Form 4, Pages 202-203

CHLORINE AND ITS COMPOUNDS

Test for Chloride Ions

By the end of the lesson, the learner should be able to:
Carry out confirmatory tests for chloride ions. Distinguish between different chloride tests. Practice qualitative analysis techniques. Write equations for chloride ion tests.

Practical work: Experiment 6.9 - Testing sodium chloride with concentrated H2SO4, testing with lead(II) nitrate solution. Recording observations in Table 6. Tests: White fumes with H2SO4 + ammonia test, white precipitate with Pb(NO3)2 that dissolves on warming. Writing equations: NaCl + H2SO4 → NaHSO4 + HCl, Pb²⁺ + 2Cl⁻ → PbCl

Sodium chloride, Concentrated H2SO4, Lead(II) nitrate solution, Aqueous ammonia, Glass rod, Test tubes, Bunsen burner

KLB Secondary Chemistry Form 4, Pages 204-205

CHLORINE AND ITS COMPOUNDS

Uses of Chlorine and its Compounds
Hydrogen Chloride - Laboratory Preparation

By the end of the lesson, the learner should be able to:
List the industrial uses of chlorine. Explain the use of chlorine in water treatment. Describe manufacture of chlorine compounds. Relate properties to uses of chlorine.

Discussion: Industrial applications - HCl manufacture, bleaching agents for cotton and paper industries, water treatment and sewage plants. Study Figure 6.3(a) - bleaching chemicals. Applications: Chloroform (anaesthetic), solvents (trichloroethane), CFCs, PVC plastics, pesticides (DDT), germicides and fungicides. Q/A: Relating chemical properties to practical applications.

Charts showing industrial uses, Samples of bleaching agents, PVC materials, Photographs of water treatment plants, Industrial application diagrams
Rock salt (NaCl), Concentrated H2SO4, Gas collection apparatus, Ammonia solution, Litmus papers, Water trough, Gas jars

KLB Secondary Chemistry Form 4, Pages 205-207

CHLORINE AND ITS COMPOUNDS

Chemical Properties of Hydrogen Chloride

By the end of the lesson, the learner should be able to:
Prepare aqueous hydrogen chloride (hydrochloric acid). Investigate acid properties of HCl solution. Test reactions with metals, bases, and carbonates. Compare HCl in water vs organic solvents.

Practical work: Experiment 6.11 - Preparation of aqueous HCl using apparatus in Figure 6. Testing with metals (Zn, Fe, Mg, Cu), NaOH, carbonates, lead nitrate. Recording observations in Table 6.7. Testing HCl in methylbenzene - no acid properties. Discussion: Ionization in water vs molecular existence in organic solvents. Writing equations for acid reactions.

Distilled water, Filter funnel, Metals (Zn, Fe, Mg, Cu), NaOH solution, Carbonates, Lead nitrate, Methylbenzene, Indicators

KLB Secondary Chemistry Form 4, Pages 208-211

CHLORINE AND ITS COMPOUNDS

Large-scale Manufacture of Hydrochloric Acid

By the end of the lesson, the learner should be able to:
Describe industrial production of hydrochloric acid. Identify raw materials and conditions used. Explain the controlled combustion process. Draw flow diagrams of the industrial process.

Study of Figure 6.4 - Large-scale manufacture setup. Discussion: Raw materials (H2 from electrolysis/cracking, Cl2 from electrolysis). Controlled combustion: H2 + Cl2 → 2HCl in jet burner. Dissolving HCl gas in water over glass beads. Safety: Explosive nature of H2/Cl2 mixture, use of excess chlorine. Industrial considerations: 35% concentration, transport in rubber-lined steel tanks.

Flow diagrams, Industrial photographs, Glass beads samples, Charts showing electrolysis processes, Safety equipment models

KLB Secondary Chemistry Form 4, Pages 211-212

CHLORINE AND ITS COMPOUNDS

Uses of Hydrochloric Acid
Environmental Pollution by Chlorine Compounds and Summary

By the end of the lesson, the learner should be able to:
List the industrial uses of hydrochloric acid. Explain applications in metal treatment. Describe use in water treatment and manufacturing. Relate acid properties to industrial applications.

Discussion: Applications - rust removal and descaling, galvanizing preparation, electroplating preparation, water treatment (chlorination), sewage treatment. Manufacturing uses: dyes, drugs, photographic materials (AgCl), pH control in industries. Q/A: How acid properties make HCl suitable for these uses. Case studies: Metal cleaning processes, water purification systems.

Samples of rusted and cleaned metals, Photographic materials, pH control charts, Industrial application videos, Water treatment diagrams
Environmental pollution charts, Ozone layer diagrams, DDT restriction documents, PVC waste samples, NEMA guidelines, Summary charts of reactions

KLB Secondary Chemistry Form 4, Pages 212-213