ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Endothermic and Exothermic Reactions
Enthalpy Notation and Energy Content

By the end of the lesson, the learner should be able to:
- Define endothermic and exothermic reactions using ΔH notation
-Investigate temperature changes when ammonium nitrate and sodium hydroxide dissolve in water
-Explain observations made during dissolution
-Draw energy level diagrams for endothermic and exothermic reactions
- Define enthalpy and enthalpy change
-Use the symbol ΔH to represent enthalpy changes
-Calculate enthalpy changes using the formula ΔH = H(products) - H(reactants)
-Distinguish between positive and negative enthalpy changes

Class experiment: Wrap 250ml plastic beakers with tissue paper. Dissolve 2 spatulafuls of NH₄NO₃ in 100ml distilled water, record temperature changes. Repeat with NaOH pellets. Compare initial and final temperatures. Draw energy level diagrams showing relative energies of reactants and products.
Q/A: Review previous experiment results. Introduce enthalpy symbol H and enthalpy change ΔH. Calculate enthalpy changes from previous experiments. Explain why endothermic reactions have positive ΔH and exothermic reactions have negative ΔH. Practice calculations with worked examples.

250ml plastic beakers, tissue paper, rubber bands, NH₄NO₃, NaOH pellets, distilled water, thermometers, spatulas, measuring cylinders
Student books, calculators, worked examples from textbook, chalkboard for calculations

KLB Secondary Chemistry Form 4, Pages 29-31
KLB Secondary Chemistry Form 4, Pages 31-32

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Bond Breaking and Bond Formation
Latent Heat of Fusion and Vaporization

By the end of the lesson, the learner should be able to:
- Explain that energy changes are due to bond breaking and bond formation
-Describe bond breaking as endothermic and bond formation as exothermic
-Investigate energy changes during melting and boiling
-Plot heating curves for pure substances

Class experiment: Heat crushed ice while stirring with thermometer. Record temperature every minute until ice melts completely, then continue until water boils. Plot temperature-time graph. Explain constant temperature during melting and boiling in terms of bond breaking. Discuss latent heat of fusion and vaporization.

Crushed pure ice, 250ml glass beakers, thermometers, heating source, stopwatch, graph paper, stirring rods
Data tables showing molar heats of fusion/vaporization, calculators, heating curves from previous lesson

KLB Secondary Chemistry Form 4, Pages 32-35

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Bond Energy Calculations

By the end of the lesson, the learner should be able to:
- Calculate energy changes in reactions using bond energies
-Apply the formula: Heat of reaction = Bond breaking energy + Bond formation energy
-Determine whether reactions are exothermic or endothermic
-Use bond energy data to solve problems

Work through formation of HCl from H₂ and Cl₂ using bond energies. Calculate energy required to break H-H and Cl-Cl bonds. Calculate energy released when H-Cl bonds form. Apply formula: ΔH = Energy absorbed - Energy released. Practice with additional examples. Discuss why calculated values may differ from experimental values.

Bond energy data tables, calculators, worked examples, practice problems

KLB Secondary Chemistry Form 4, Pages 35-36

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Determination of Enthalpy of Solution I

By the end of the lesson, the learner should be able to:
- Determine the enthalpy changes of solution of ammonium nitrate and sodium hydroxide
-Calculate enthalpy change using ΔH = mcΔT
-Calculate number of moles of solute dissolved
-Determine molar heat of solution

Class experiment: Dissolve exactly 2.0g NH₄NO₃ in 100ml distilled water in plastic beaker. Record temperature change. Repeat with 2.0g NaOH. Calculate enthalpy changes using ΔH = mcΔT where m = 100g, c = 4.2 kJ kg⁻¹K⁻¹. Calculate moles dissolved and molar heat of solution.

250ml plastic beakers, 2.0g samples of NH₄NO₃ and NaOH, distilled water, thermometers, measuring cylinders, analytical balance, calculators

KLB Secondary Chemistry Form 4, Pages 36-38

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Thermochemical Equations
Enthalpy of Solution of Concentrated Sulphuric Acid

By the end of the lesson, the learner should be able to:
- Write thermochemical equations including enthalpy changes
-Define molar heat of solution
-Draw energy level diagrams for dissolution reactions
-Interpret thermochemical equations correctly
- Determine heat of solution of concentrated sulphuric(VI) acid
-Apply safety precautions when handling concentrated acids
-Calculate enthalpy change considering density and purity
-Write thermochemical equation for the reaction

Using data from previous experiment, write thermochemical equations for NH₄NO₃ and NaOH dissolution. Show proper notation with state symbols and ΔH values. Draw corresponding energy level diagrams. Practice writing thermochemical equations for various reactions. Explain significance of molar quantities in equations.
Teacher demonstration: Carefully add 2cm³ concentrated H₂SO₄ to 98cm³ distilled water in wrapped beaker (NEVER vice versa). Record temperature change. Calculate mass of acid using density (1.84 g/cm³) and purity (98%). Calculate molar heat of solution. Emphasize safety - always add acid to water.

Results from previous experiment, graph paper for energy level diagrams, practice examples
Concentrated H₂SO₄, distilled water, 250ml plastic beaker, tissue paper, measuring cylinders, thermometer, safety equipment

KLB Secondary Chemistry Form 4, Pages 38-39
KLB Secondary Chemistry Form 4, Pages 39-41

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Enthalpy of Combustion
Enthalpy of Displacement

By the end of the lesson, the learner should be able to:
- Define molar heat of combustion
-Determine enthalpy of combustion of ethanol experimentally
-Explain why experimental values differ from theoretical values
-Calculate molar enthalpy of combustion from experimental data

Class experiment: Burn ethanol in small bottle with wick to heat 100cm³ water in glass beaker. Record initial and final masses of bottle+ethanol and temperature change. Calculate moles of ethanol burned and heat evolved. Determine molar enthalpy of combustion. Compare with theoretical value (-1368 kJ/mol). Discuss sources of error.

Ethanol, small bottles with wicks, 250ml glass beakers, tripod stands, wire gauze, thermometers, analytical balance, measuring cylinders
Zinc powder, 0.5M CuSO₄ solution, 250ml plastic beakers, tissue paper, thermometers, analytical balance, stirring rods

KLB Secondary Chemistry Form 4, Pages 41-44

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Enthalpy of Neutralization

By the end of the lesson, the learner should be able to:
- Define molar heat of neutralization
-Determine heat of neutralization of HCl with NaOH
-Compare neutralization enthalpies of strong and weak acids/bases
-Write ionic equations for neutralization reactions

Class experiment: Mix 50cm³ of 2M HCl with 50cm³ of 2M NaOH in wrapped beaker. Record temperature changes. Calculate molar heat of neutralization. Repeat with weak acid (ethanoic) and weak base (ammonia). Compare values. Write ionic equations. Explain why strong acid + strong base gives ~57.2 kJ/mol.

2M HCl, 2M NaOH, 2M ethanoic acid, 2M ammonia solution, measuring cylinders, thermometers, 250ml plastic beakers, tissue paper

KLB Secondary Chemistry Form 4, Pages 47-49

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Standard Conditions and Standard Enthalpy Changes

By the end of the lesson, the learner should be able to:
- Identify standard conditions for measuring enthalpy changes
-Define standard enthalpy changes using ΔH° notation
-Explain importance of standard conditions
-Use subscripts to denote different types of enthalpy changes

Q/A: Review previous enthalpy measurements. Introduce standard conditions: 25°C (298K) and 1 atmosphere pressure (101.325 kPa). Explain ΔH° notation and subscripts (ΔH°c for combustion, ΔH°f for formation, etc.). Discuss why standard conditions are necessary for comparison. Practice using correct notation.

Student books, examples of standard enthalpy data, notation practice exercises

KLB Secondary Chemistry Form 4, Pages 49

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Hess's Law - Introduction and Theory
Energy Cycle Diagrams

By the end of the lesson, the learner should be able to:
- State Hess's Law
-Explain the principle of energy conservation in chemical reactions
-Understand that enthalpy change is independent of reaction route
-Apply Hess's Law to simple examples
- Draw energy cycle diagrams
-Link enthalpy of formation with enthalpy of combustion
-Calculate unknown enthalpy changes using energy cycles
-Apply Hess's Law to determine enthalpy of formation

Introduce Hess's Law: "The energy change in converting reactants to products is the same regardless of the route by which the chemical change occurs." Use methane formation example to show two routes giving same overall energy change. Draw energy cycle diagrams. Explain law of conservation of energy application.
Work through energy cycle for formation of CO from carbon and oxygen using combustion data. Draw cycle showing Route 1 (direct combustion) and Route 2 (formation then combustion). Calculate ΔH°f(CO) = ΔH°c(C) - ΔH°c(CO). Practice with additional examples including ethanol formation.

Energy cycle diagrams for methane formation, chalkboard illustrations, worked examples from textbook
Graph paper, energy cycle templates, combustion data tables, calculators

KLB Secondary Chemistry Form 4, Pages 49-52
KLB Secondary Chemistry Form 4, Pages 52-54

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Hess's Law Calculations
Lattice Energy and Hydration Energy

By the end of the lesson, the learner should be able to:
- Solve complex problems using Hess's Law
-Apply energy cycles to multi-step reactions
-Calculate enthalpy of formation from combustion data
-Use thermochemical equations in Hess's Law problems

Work through detailed calculation for ethanol formation: 2C(s) + 3H₂(g) + ½O₂(g) → C₂H₅OH(l). Use combustion enthalpies of carbon (-393 kJ/mol), hydrogen (-286 kJ/mol), and ethanol (-1368 kJ/mol). Calculate ΔH°f(ethanol) = -278 kJ/mol. Practice with propane and other compounds.

Worked examples, combustion data, calculators, step-by-step calculation sheets
Energy cycle diagrams, lattice energy and hydration energy data tables, calculators

KLB Secondary Chemistry Form 4, Pages 54-56

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Factors Affecting Lattice and Hydration Energies

By the end of the lesson, the learner should be able to:
- Explain factors affecting lattice energy
-Explain factors affecting hydration energy
-Use data tables to identify trends
-Calculate enthalpies of solution for various ionic compounds

Analyze data tables showing lattice energies (Table 2.7) and hydration energies (Table 2.6). Identify trends: smaller ions and higher charges give larger lattice energies and hydration energies. Calculate heat of solution for MgCl₂ using: ΔH(solution) = +2489 + (-1891 + 2×(-384)) = -170 kJ/mol. Practice with other compounds.

Data tables from textbook, calculators, trend analysis exercises

KLB Secondary Chemistry Form 4, Pages 54-56

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Definition and Types of Fuels

By the end of the lesson, the learner should be able to:
- Define a fuel
-Classify fuels as solid, liquid, or gaseous
-State examples of each type of fuel
-Explain energy conversion in fuel combustion

Q/A: List fuels used at home and school. Define fuel as "substance that produces useful energy when it undergoes chemical or nuclear reaction." Classify examples: solids (coal, charcoal, wood), liquids (petrol, kerosene, diesel), gases (natural gas, biogas, LPG). Discuss energy conversions during combustion.

Examples of different fuels, classification charts, pictures of fuel types

KLB Secondary Chemistry Form 4, Pages 56

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Heating Values of Fuels
Factors in Fuel Selection

By the end of the lesson, the learner should be able to:
- Define heating value of a fuel
-Calculate heating values from molar enthalpies of combustion
-Compare heating values of different fuels
-Explain units of heating value (kJ/g)
- State factors that influence choice of fuel
-Explain why different fuels are chosen for different purposes
-Compare advantages and disadvantages of various fuels
-Apply selection criteria to real situations

Calculate heating value of ethanol: ΔH°c = -1360 kJ/mol, Molar mass = 46 g/mol, Heating value = 1360/46 = 30 kJ/g. Compare heating values from Table 2.8: methane (55 kJ/g), fuel oil (45 kJ/g), charcoal (33 kJ/g), wood (17 kJ/g). Discuss significance of these values for fuel selection.
Discuss seven factors: heating value, ease of combustion, availability, transportation, storage, environmental effects, cost. Compare wood/charcoal for domestic use vs methylhydrazine for rockets. Analyze why each is suitable for its purpose. Students suggest best fuels for cooking, heating, transport in their area.

Heating value data table, calculators, fuel comparison charts
Fuel comparison tables, local fuel availability data, cost analysis sheets

KLB Secondary Chemistry Form 4, Pages 56-57
KLB Secondary Chemistry Form 4, Pages 57

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Environmental Effects of Fuels
Fuel Safety and Precautions

By the end of the lesson, the learner should be able to:
- Identify environmental effects of burning fuels
-Explain formation and effects of acid rain
-Describe contribution to global warming
-State measures to reduce pollution from fuels

Discuss pollutants from fossil fuels: SO₂, SO₃, CO, NO₂ causing acid rain. Effects: damage to buildings, corrosion, acidification of lakes, soil leaching. CO₂ and hydrocarbons cause global warming leading to ice melting, climate change. Pollution reduction measures: catalytic converters, unleaded petrol, zero emission vehicles, alternative fuels.

Pictures of environmental damage, pollution data, examples of clean technology
Safety guideline charts, examples of fuel accidents, local safety case studies

KLB Secondary Chemistry Form 4, Pages 57-58

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Endothermic and Exothermic Reactions

By the end of the lesson, the learner should be able to:
- Define endothermic and exothermic reactions using the ΔH notation
-Investigate what happens when ammonium nitrate and sodium hydroxide are separately dissolved in water
-Define enthalpy and enthalpy change
-Calculate enthalpy changes using ΔH = H(products) - H(reactants)

Class experiment: Dissolve NH₄NO₃ and NaOH separately in water, record temperature changes in Table 2.1. Explain heat absorption vs evolution. Introduce enthalpy (H) and enthalpy change (ΔH). Calculate enthalpy changes from experimental data. Draw energy level diagrams showing relative energies.

250ml plastic beakers, tissue paper, NH₄NO₃, NaOH pellets, distilled water, thermometers, calculators

KLB Secondary Chemistry Form 4, Pages 29-32

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Bond Breaking, Formation and Phase Changes

By the end of the lesson, the learner should be able to:
- Explain that energy changes are due to bond breaking and bond formation
-Investigate energy changes when solids and liquids are heated
-Define latent heat of fusion and vaporization
-Calculate energy changes using bond energies

Class experiment: Heat ice to melting then boiling, record temperature every minute. Plot heating curve. Explain constant temperature periods. Define latent heat of fusion/vaporization. Calculate energy changes in H₂ + Cl₂ → 2HCl using bond energies. Apply formula: ΔH = Energy absorbed - Energy released.

Ice, glass beakers, thermometers, heating source, graph paper, bond energy data tables

KLB Secondary Chemistry Form 4, Pages 32-36

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Determination of Enthalpy of Solution
Enthalpy of Solution of H₂SO₄ and Safety

By the end of the lesson, the learner should be able to:
- Carry out experiments to determine enthalpy changes of solution
-Calculate enthalpy change using ΔH = mcΔT
-Write correct thermochemical equations
-Define molar heat of solution
- Determine heat of solution of concentrated sulphuric(VI) acid
-Apply safety precautions when handling concentrated acids
-Calculate enthalpy considering density and percentage purity
-Explain why experimental values differ from theoretical values

Class experiment: Dissolve exactly 2.0g NH₄NO₃ and 2.0g NaOH separately in 100ml water. Record temperature changes. Calculate enthalpy changes using ΔH = mcΔT. Calculate moles and molar heat of solution. Write thermochemical equations: NH₄NO₃(s) + aq → NH₄NO₃(aq) ΔH = +25.2 kJ mol⁻¹.
Teacher demonstration: Add 2cm³ concentrated H₂SO₄ to 98cm³ water (NEVER vice versa). Record temperature change. Calculate mass using density (1.84 g/cm³) and purity (98%). Calculate molar heat of solution. Emphasize safety: always add acid to water. Discuss sources of experimental error.

2.0g samples of NH₄NO₃ and NaOH, plastic beakers, thermometers, analytical balance, calculators
Concentrated H₂SO₄, distilled water, plastic beaker, tissue paper, thermometer, safety equipment

KLB Secondary Chemistry Form 4, Pages 36-39
KLB Secondary Chemistry Form 4, Pages 39-41

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Enthalpy of Combustion

By the end of the lesson, the learner should be able to:
- Carry out experiments to determine enthalpy of combustion of ethanol
-Define molar heat of combustion
-Calculate molar enthalpy of combustion from experimental data
-Explain why actual heats are lower than theoretical values

Class experiment: Burn ethanol to heat 100cm³ water. Record mass of ethanol burned and temperature change. Calculate moles of ethanol and heat evolved using ΔH = mcΔT. Determine molar enthalpy of combustion. Compare with theoretical (-1368 kJ/mol). Discuss heat losses to surroundings.

Ethanol, bottles with wicks, glass beakers, tripod stands, thermometers, analytical balance

KLB Secondary Chemistry Form 4, Pages 41-44

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Enthalpy of Displacement
Enthalpy of Neutralization

By the end of the lesson, the learner should be able to:
- Investigate enthalpy change when zinc reacts with copper(II) sulphate
-Define molar heat of displacement
-Calculate molar heat of displacement from experimental data
-Explain relationship between reactivity series and heat evolved

Class experiment: Add 4.0g zinc powder to 100cm³ of 0.5M CuSO₄. Record temperature change and observations (blue color fades, brown solid). Calculate moles and molar heat of displacement. Write ionic equation: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s). Explain why excess zinc is used.

Zinc powder, 0.5M CuSO₄ solution, plastic beakers, thermometers, analytical balance
2M HCl, 2M NaOH, 2M ethanoic acid, 2M ammonia solution, measuring cylinders, thermometers, plastic beakers

KLB Secondary Chemistry Form 4, Pages 44-47

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Standard Conditions and Standard Enthalpy Changes

By the end of the lesson, the learner should be able to:
- Define standard conditions for measuring enthalpy changes
-Use standard enthalpy notation ΔH°
-Apply correct notation for different types of enthalpy changes
-Explain importance of standardization for comparison

Q/A: Review enthalpy measurements. Define standard conditions: 25°C (298K) and 1 atmosphere (101.325 kPa). Introduce ΔH° notation where θ denotes standard. Show subscripts: ΔH°c (combustion), ΔH°f (formation), ΔH°neut (neutralization), ΔH°sol (solution). Practice using correct notation in thermochemical equations.

Student books, standard enthalpy data examples, notation practice exercises

KLB Secondary Chemistry Form 4, Pages 49

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Hess's Law - Theory and Energy Cycles
Hess's Law Calculations

By the end of the lesson, the learner should be able to:
- State Hess's Law
-Explain that enthalpy change is independent of reaction route
-Draw energy cycle diagrams
-Apply Hess's Law to determine enthalpy of formation
- Carry out calculations using Hess's Law
-Draw energy level diagrams
-Calculate enthalpy of formation from combustion data
-Solve worked examples using energy cycles

Introduce Hess's Law: "Energy change in converting reactants to products is same regardless of route." Use methane formation showing Route 1 (direct combustion) vs Route 2 (formation then combustion). Draw energy cycle. Calculate ΔH°f(CH₄) = -965 + (-890) - (-75) = -75 kJ/mol. Practice with CO formation example.
Work through ethanol formation: 2C(s) + 3H₂(g) + ½O₂(g) → C₂H₅OH(l). Draw energy cycle and level diagrams. Apply: ΔH°f(ethanol) = 2×ΔH°c(C) + 3×ΔH°c(H₂) - ΔH°c(ethanol) = 2×(-393) + 3×(-286) - (-1368) = -278 kJ/mol. Practice additional calculations from revision exercises.

Energy cycle diagrams for methane and CO formation, combustion data, calculators
Worked examples, combustion data tables, graph paper for diagrams, calculators

KLB Secondary Chemistry Form 4, Pages 49-52
KLB Secondary Chemistry Form 4, Pages 52-56

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Lattice Energy and Hydration Energy

By the end of the lesson, the learner should be able to:
- Explain relationship between heat of solution, hydration and lattice energy
-Define lattice energy and hydration energy
-Draw energy cycles for dissolving ionic compounds
-Calculate heat of solution using energy cycles

Explain NaCl dissolution: lattice breaks (endothermic) then ions hydrate (exothermic). Define lattice energy as energy when ionic compound forms from gaseous ions. Define hydration energy as energy when gaseous ions become hydrated. Draw energy cycle: ΔH(solution) = ΔH(lattice) + ΔH(hydration). Calculate for NaCl: +781 + (-774) = +7 kJ/mol.

Energy cycle diagrams, hydration diagram (Fig 2.17), Tables 2.6 and 2.7 with lattice/hydration energies

KLB Secondary Chemistry Form 4, Pages 54-56

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Definition and Types of Fuels
Fuel Selection Factors

By the end of the lesson, the learner should be able to:
- Define a fuel
-Classify fuels into solid, liquid and gaseous types
-Define heating value of a fuel
-Calculate heating values from molar enthalpies of combustion

Define fuel as "substance producing useful energy in chemical/nuclear reaction." Classify: solids (coal, charcoal, wood), liquids (petrol, kerosene, diesel), gases (natural gas, biogas, LPG). Define heating value as "heat energy per unit mass." Calculate for ethanol: -1360 kJ/mol ÷ 46 g/mol = 30 kJ/g. Compare values from Table 2.8.

Examples of local fuels, Table 2.8 showing heating values, calculators
Fuel comparison tables, local fuel cost data, examples of specialized fuel applications

KLB Secondary Chemistry Form 4, Pages 56-57

ENERGY CHANGES IN PHYSICAL AND CHEMICAL PROCESSES

Environmental Effects and Safety

By the end of the lesson, the learner should be able to:
- Explain environmental effects of fuels
-Describe formation and effects of acid rain
-Identify measures to reduce pollution
-State safety precautions for fuel handling

Discuss pollutants: SO₂, NO₂ forming acid rain affecting buildings, lakes, vegetation. CO₂ causing global warming and climate change. Pollution reduction: catalytic converters, unleaded petrol, zero emission vehicles, alternative fuels. Safety: ventilation for charcoal, proper gas storage, fuel storage location, avoiding spills.

Pictures of environmental damage, pollution reduction examples, safety guideline charts

KLB Secondary Chemistry Form 4, Pages 57-58

REACTION RATES AND REVERSIBLE REACTIONS

Definition of Reaction Rate and Collision Theory
Effect of Concentration on Reaction Rate

By the end of the lesson, the learner should be able to:
- Define rate of reaction and explain the term activation energy
-Describe collision theory and explain why not all collisions result in products
-Draw energy diagrams showing activation energy
-Explain how activation energy affects reaction rates
- Explain the effect of concentration on reaction rates
-Investigate reaction of magnesium with different concentrations of sulphuric acid
-Illustrate reaction rates graphically and interpret experimental data
-Calculate concentrations and plot graphs of concentration vs time

Q/A: Compare speeds of different reactions (precipitation vs rusting). Define reaction rate as "measure of how much reactants are consumed or products formed per unit time." Introduce collision theory: particles must collide with minimum energy (activation energy) for successful reaction. Draw energy diagram showing activation energy barrier. Discuss factors affecting collision frequency and energy.
Class experiment: Label 4 conical flasks A-D. Add 40cm³ of 2M H₂SO₄ to A, dilute others with water (30+10, 20+20, 10+30 cm³). Drop 2cm magnesium ribbon into each, time complete dissolution. Record in Table 3.1. Calculate concentrations, plot graph. Explain: higher concentration → more collisions → faster reaction.

Examples of fast/slow reactions, energy diagram templates, chalk/markers for diagrams
4 conical flasks, 2M H₂SO₄, distilled water, magnesium ribbon, stopwatch, measuring cylinders, graph paper

KLB Secondary Chemistry Form 4, Pages 64-65
KLB Secondary Chemistry Form 4, Pages 65-67

REACTION RATES AND REVERSIBLE REACTIONS

Change of Reaction Rate with Time

By the end of the lesson, the learner should be able to:
- Describe methods used to measure rate of reaction
-Investigate how reaction rate changes as reaction proceeds
-Plot graphs of volume of gas vs time
-Calculate average rates at different time intervals

Class experiment: React 2cm magnesium ribbon with 100cm³ of 0.5M HCl in conical flask. Collect H₂ gas in graduated syringe as in Fig 3.4. Record gas volume every 30 seconds for 5 minutes in Table 3.2. Plot volume vs time graph. Calculate average rates between time intervals. Explain why rate decreases as reactants are consumed.

0.5M HCl, magnesium ribbon, conical flask, gas collection apparatus, graduated syringe, stopwatch, graph paper

KLB Secondary Chemistry Form 4, Pages 67-70

REACTION RATES AND REVERSIBLE REACTIONS

Effect of Temperature on Reaction Rate
Effect of Surface Area on Reaction Rate

By the end of the lesson, the learner should be able to:
- Explain the effect of temperature on reaction rates
-Investigate temperature effects using sodium thiosulphate and HCl
-Plot graphs of time vs temperature and 1/time vs temperature
-Apply collision theory to explain temperature effects

Class experiment: Place 30cm³ of 0.15M Na₂S₂O₃ in flasks at room temp, 30°C, 40°C, 50°C, 60°C. Mark cross on paper under flask. Add 5cm³ of 2M HCl, time until cross disappears. Record in Table 3.4. Plot time vs temperature and 1/time vs temperature graphs. Explain: higher temperature → more kinetic energy → more effective collisions.

0.15M Na₂S₂O₃, 2M HCl, conical flasks, water baths at different temperatures, paper with cross marked, stopwatch, thermometers
Marble chips, marble powder, 1M HCl, gas collection apparatus, balance, conical flasks, measuring cylinders, graph paper

KLB Secondary Chemistry Form 4, Pages 70-73

REACTION RATES AND REVERSIBLE REACTIONS

Effect of Catalysts on Reaction Rate

By the end of the lesson, the learner should be able to:
- Explain effects of suitable catalysts on reaction rates
-Investigate decomposition of hydrogen peroxide with and without catalyst
-Define catalyst and explain how catalysts work
-Compare activation energies in catalyzed vs uncatalyzed reactions

Class experiment: Decompose 5cm³ of 20-volume H₂O₂ in 45cm³ water without catalyst, collect O₂ gas. Repeat adding 2g MnO₂ powder. Record gas volumes as in Fig 3.12. Compare rates and final mass of MnO₂. Write equation: 2H₂O₂ → 2H₂O + O₂. Define catalyst and explain how it lowers activation energy. Show energy diagrams for both pathways.

20-volume H₂O₂, MnO₂ powder, gas collection apparatus, balance, conical flasks, filter paper, measuring cylinders

KLB Secondary Chemistry Form 4, Pages 76-78

REACTION RATES AND REVERSIBLE REACTIONS

Effect of Light and Pressure on Reaction Rate
Reversible Reactions

By the end of the lesson, the learner should be able to:
- Identify reactions affected by light
-Investigate effect of light on silver bromide decomposition
-Explain effect of pressure on gaseous reactions
-Give examples of photochemical reactions
- State examples of simple reversible reactions
-Investigate heating of hydrated copper(II) sulphate
-Write equations for reversible reactions using double arrows
-Distinguish between reversible and irreversible reactions

Teacher demonstration: Mix KBr and AgNO₃ solutions to form AgBr precipitate. Divide into 3 test tubes: place one in dark cupboard, one on bench, one in direct sunlight. Observe color changes after 10 minutes. Write equations. Discuss photochemical reactions: photography, Cl₂ + H₂, photosynthesis. Explain pressure effects on gaseous reactions through compression.
Class experiment: Heat CuSO₄·5H₂O crystals in boiling tube A, collect liquid in tube B as in Fig 3.15. Observe color changes: blue → white + colorless liquid. Pour liquid back into tube A, observe return to blue. Write equation with double arrows: CuSO₄·5H₂O ⇌ CuSO₄ + 5H₂O. Give other examples: NH₄Cl ⇌ NH₃ + HCl. Compare with irreversible reactions.

0.1M KBr, 0.05M AgNO₃, test tubes, dark cupboard, direct light source, examples of photochemical reactions
CuSO₄·5H₂O crystals, boiling tubes, delivery tube, heating source, test tube holder

KLB Secondary Chemistry Form 4, Pages 78-80

REACTION RATES AND REVERSIBLE REACTIONS

Chemical Equilibrium

By the end of the lesson, the learner should be able to:
- Explain chemical equilibrium
-Define dynamic equilibrium
-Investigate acid-base equilibrium using indicators
-Explain why equilibrium appears static but is actually dynamic

Experiment: Add 0.5M NaOH to 2cm³ in boiling tube with universal indicator. Add 0.5M HCl dropwise until green color (neutralization point). Continue adding base then acid alternately, observe color changes. Explain equilibrium as state where forward and backward reaction rates are equal. Use NH₄Cl ⇌ NH₃ + HCl example to show dynamic nature. Introduce equilibrium symbol ⇌.

0.5M NaOH, 0.5M HCl, universal indicator, boiling tubes, droppers, examples of equilibrium systems

KLB Secondary Chemistry Form 4, Pages 80-82

REACTION RATES AND REVERSIBLE REACTIONS

Le Chatelier's Principle and Effect of Concentration
Effect of Pressure and Temperature on Equilibrium

By the end of the lesson, the learner should be able to:
- State Le Chatelier's Principle
-Explain effect of concentration changes on equilibrium position
-Investigate bromine water equilibrium with acid/base addition
-Apply Le Chatelier's Principle to predict equilibrium shifts

Experiment: Add 2M NaOH dropwise to 20cm³ bromine water until colorless. Then add 2M HCl until excess, observe color return. Write equation: Br₂ + H₂O ⇌ HBr + HBrO. Explain Le Chatelier's Principle: "When change applied to system at equilibrium, system moves to oppose that change." Demonstrate with chromate/dichromate equilibrium: CrO₄²⁻ + H⁺ ⇌ Cr₂O₇²⁻ + H₂O.

Bromine water, 2M NaOH, 2M HCl, beakers, chromate/dichromate solutions for demonstration
Copper turnings, concentrated HNO₃, test tubes, heating source, ice bath, gas collection apparatus, safety equipment

KLB Secondary Chemistry Form 4, Pages 82-84

REACTION RATES AND REVERSIBLE REACTIONS

Industrial Applications - Haber Process

By the end of the lesson, the learner should be able to:
- Apply equilibrium principles to Haber Process
-Explain optimum conditions for ammonia manufacture
-Calculate effect of temperature and pressure on yield
-Explain role of catalysts in industrial processes

Analyze Haber Process: N₂ + 3H₂ ⇌ 2NH₃ ΔH = -92 kJ/mol. Apply Le Chatelier's Principle: high pressure favors forward reaction (4 molecules → 2 molecules), low temperature favors exothermic forward reaction but slows rate. Explain optimum conditions: 450°C temperature, 200 atmospheres pressure, iron catalyst. Discuss removal of NH₃ to shift equilibrium right. Economic considerations.

Haber Process flow diagram, equilibrium data showing temperature/pressure effects on NH₃ yield, industrial catalyst information

KLB Secondary Chemistry Form 4, Pages 87-89

REACTION RATES AND REVERSIBLE REACTIONS
ELECTROCHEMISTRY

Industrial Applications - Contact Process
Redox Reactions and Oxidation Numbers
Oxidation Numbers in Naming and Redox Identification
Displacement Reactions - Metals and Halogens

By the end of the lesson, the learner should be able to:
- Apply equilibrium principles to Contact Process
-Explain optimum conditions for sulphuric acid manufacture
-Compare different industrial equilibrium processes
-Evaluate economic factors in industrial chemistry
Define redox reactions in terms of electron transfer
- State rules for assigning oxidation numbers
- Calculate oxidation numbers in compounds
- Identify oxidation and reduction processes

Analyze Contact Process: 2SO₂ + O₂ ⇌ 2SO₃ ΔH = -197 kJ/mol. Apply principles: high pressure favors forward reaction (3 molecules → 2 molecules), low temperature favors exothermic reaction. Explain optimum conditions: 450°C, atmospheric pressure, V₂O₅ catalyst, 96% conversion. Compare with Haber Process. Discuss catalyst choice and economic factors.
Q/A: Review previous knowledge
- Experiment 4.1: Iron filings + copper(II) sulphate
- Experiment 4.2: Iron(II) ions + hydrogen peroxide
- Discussion on oxidation number rules with examples

Contact Process flow diagram, comparison table with Haber Process, catalyst effectiveness data
Iron filings, 1M CuSO₄, 1M FeSO₄, 2M NaOH, 20V H₂O₂, test tubes
Compound charts, calculators, student books, practice exercises
Various metals (Ca, Mg, Zn, Fe, Pb, Cu), metal salt solutions, halogens (Cl₂, Br₂, I₂), halide solutions

KLB Secondary Chemistry Form 4, Pages 89
KLB Secondary Chemistry Form 4, Pages 108-116

ELECTROCHEMISTRY

Electrochemical Cells and Cell Diagrams
Standard Electrode Potentials

By the end of the lesson, the learner should be able to:
Define electrode potential and EMF
- Describe electrochemical cell components
- Draw cell diagrams using correct notation
- Explain electron flow and salt bridge function

Experiment 4.5: Set up Zn/Cu cell and other metal combinations
- Measure EMF values
- Practice writing cell notation
- Learn conventional representation methods

Metal electrodes, 1M metal salt solutions, voltmeters, salt bridges, connecting wires
Standard electrode potential table, diagrams, charts showing standard conditions

KLB Secondary Chemistry Form 4, Pages 123-128

ELECTROCHEMISTRY

Calculating Cell EMF and Predicting Reactions
Types of Electrochemical Cells

By the end of the lesson, the learner should be able to:
Calculate EMF using standard electrode potentials
- Predict reaction spontaneity using EMF
- Solve numerical problems on cell EMF
- Apply EMF calculations practically

Worked examples: Calculate EMF for various cells
- Practice EMF calculations
- Exercise 4.2 & 4.3: Cell EMF and reaction feasibility problems
- Distinguish spontaneous from non-spontaneous reactions

Calculators, electrode potential data, worked examples, practice problems
Cell diagrams, sample batteries, charts showing cell applications

KLB Secondary Chemistry Form 4, Pages 133-137

ELECTROCHEMISTRY

Electrolysis of Aqueous Solutions I
Electrolysis of Aqueous Solutions II

By the end of the lesson, the learner should be able to:
Define electrolysis and preferential discharge
- Investigate electrolysis of dilute sodium chloride
- Compare dilute vs concentrated solution effects
- Test products formed

Experiment 4.6(a): Electrolysis of dilute NaCl
- Experiment 4.6(b): Electrolysis of brine
- Test gases evolved
- Compare results and explain differences

Dilute and concentrated NaCl solutions, carbon electrodes, gas collection tubes, test equipment
U-tube apparatus, 2M H₂SO₄, 0.5M MgSO₄, platinum/carbon electrodes, gas syringes

KLB Secondary Chemistry Form 4, Pages 141-146

ELECTROCHEMISTRY

Effect of Electrode Material on Electrolysis
Factors Affecting Electrolysis
Applications of Electrolysis I

By the end of the lesson, the learner should be able to:
Compare inert vs reactive electrodes
- Investigate electrode dissolution
- Explain electrode selection importance
- Analyze copper purification process
Identify factors affecting preferential discharge
- Explain electrochemical series influence
- Discuss concentration and electrode effects
- Predict electrolysis products

Experiment 4.9: Electrolysis of CuSO₄ with carbon vs copper electrodes
- Weigh electrodes before/after
- Observe color changes
- Discussion on electrode effects
Review electrochemical series and discharge order
- Analysis of concentration effects on product formation
- Summary of all factors affecting electrolysis
- Practice prediction problems

Copper and carbon electrodes, 3M CuSO₄ solution, accurate balance, beakers, connecting wires
Electrochemical series chart, summary tables, practice exercises, student books
Iron nails, copper electrodes, CuSO₄ solution, power supply, industrial process diagrams

KLB Secondary Chemistry Form 4, Pages 141-148
KLB Secondary Chemistry Form 4, Pages 153-155

ELECTROCHEMISTRY

Applications of Electrolysis II

By the end of the lesson, the learner should be able to:
Describe manufacture of NaOH and Cl₂ from brine
- Explain mercury cell operation
- Analyze industrial electrolysis processes
- Discuss environmental considerations

Study mercury cell for NaOH production
- Flow chart analysis of industrial processes
- Discussion on applications and environmental impact
- Purification of metals

Flow charts, mercury cell diagrams, environmental impact data, industrial case studies

KLB Secondary Chemistry Form 4, Pages 155-157

ELECTROCHEMISTRY

Faraday's Laws and Quantitative Electrolysis

By the end of the lesson, the learner should be able to:
State Faraday's laws of electrolysis
- Define Faraday constant
- Calculate mass deposited in electrolysis
- Relate electricity to amount of substance

Experiment 4.10: Quantitative electrolysis of CuSO₄
- Measure mass vs electricity passed
- Calculate Faraday constant
- Verify Faraday's laws

Accurate balance, copper electrodes, CuSO₄ solution, ammeter, timer, calculators

KLB Secondary Chemistry Form 4, Pages 161-164

ELECTROCHEMISTRY

Electrolysis Calculations I

By the end of the lesson, the learner should be able to:
Calculate mass of products from electrolysis
- Determine volumes of gases evolved
- Apply Faraday's laws to numerical problems
- Solve basic electrolysis calculations

Worked examples: Mass and volume calculations
- Problems involving different ions
- Practice with Faraday constant
- Basic numerical problems

Calculators, worked examples, practice problems, gas volume data, Faraday constant

KLB Secondary Chemistry Form 4, Pages 161-164

ELECTROCHEMISTRY
ELECTROCHEMISTRY
METALS
METALS

Electrolysis Calculations II
Advanced Applications and Problem Solving
Chief Ores of Metals and General Extraction Methods
Occurrence and Extraction of Sodium

By the end of the lesson, the learner should be able to:
Determine charge on ions from electrolysis data
- Calculate current-time relationships
- Solve complex multi-step problems
- Apply concepts to industrial situations
Solve examination-type electrochemistry problems
- Apply all concepts in integrated problems
- Analyze real-world electrochemical processes
- Practice complex calculations

Complex problems: Determine ionic charges
- Current-time-mass relationships
- Multi-step calculations
- Industrial calculation examples
Comprehensive problems combining redox, cells, and electrolysis
- Past examination questions
- Industrial case study analysis
- Advanced problem-solving techniques

Calculators, complex problem sets, industrial data, student books
Past papers, comprehensive problem sets, industrial case studies, calculators
Chart of metal ores, ore samples if available, Table 5.1, flotation apparatus demonstration
Down's cell diagram, charts showing sodium occurrence, electrode reaction equations

KLB Secondary Chemistry Form 4, Pages 161-164
KLB Secondary Chemistry Form 4, Pages 108-164

METALS

Occurrence and Extraction of Aluminium I
Extraction of Aluminium II - Electrolysis

By the end of the lesson, the learner should be able to:
Describe occurrence and ores of aluminium
- Explain ore concentration process
- Write equations for bauxite purification
- Describe amphoteric nature of aluminium oxide

Study aluminium occurrence and bauxite composition
- Demonstration of amphoteric properties
- Equations for bauxite dissolution in NaOH
- Discussion on impurity removal

Bauxite samples, NaOH solution, charts showing aluminium extraction steps, chemical equations
Electrolytic cell diagram, cryolite samples, graphite electrodes, energy consumption data

KLB Secondary Chemistry Form 4, Pages 142-143

METALS

Occurrence and Extraction of Iron
Extraction of Zinc

By the end of the lesson, the learner should be able to:
Describe iron ores and occurrence
- Explain blast furnace operation
- Write equations for iron extraction reactions
- Describe slag formation process

Study iron ores and blast furnace structure
- Analysis of temperature zones in furnace
- Write reduction equations
- Discussion on limestone role and slag formation

Blast furnace diagram, iron ore samples, coke, limestone, temperature zone charts
Zinc ore samples, flow charts showing both methods, electrolytic cell diagrams

KLB Secondary Chemistry Form 4, Pages 143-145

METALS

Extraction of Lead and Copper
Physical Properties of Metals

By the end of the lesson, the learner should be able to:
Explain extraction of lead from galena
- Describe copper extraction from copper pyrites
- Write relevant chemical equations
- Compare purification methods

Study galena roasting and reduction
- Copper pyrites multi-step extraction
- Electrolytic purification processes
- Discussion on blister copper formation

Lead and copper ore samples, extraction flow charts, electrolytic purification diagrams
Table 5.2, metal samples, conductivity apparatus, density measurement equipment

KLB Secondary Chemistry Form 4, Pages 148-151