Unit 3: Chemical Equilibrium Systems
Not publishedof exam
Dynamic Equilibrium & KcReaction Quotient Q & ShiftsSolubility Product KspFoundational Gas & Enthalpy
Unit 3: Acids, Bases & Titrations
Not publishedof exam
Brønsted-Lowry, pH & KwWeak Acids, Ka, Kb & pKaBuffers & Indicator SelectionTitration Curves & Glassware
Unit 3: Redox & Electrochemistry
Not publishedof exam
Oxidation Numbers & KOHESGalvanic Cells & Standard E°Electrolytic Cells & RefiningFaraday's Electrolysis Laws
Unit 4: Organic & Macromolecules
Not publishedof exam
Functional groups and isomersReactions and pathwaysPolymer structure and propertiesAmino acids and carbohydrates
Unit 4: Synthesis, Yield & Spectroscopy
Not publishedof exam
Synthesis and industrial conditionsYield and limiting reagentsIR and mass spectraTLC and electrophoresis
Quick Facts
- Authority
- QCAA Queensland Year 12
- External Weight
- 50% of final subject result
- Internal Weight
- IA1 10%, IA2 20%, IA3 20%
- Exam Format
- Two combination-response papers
- Question Count
- No fixed total published
- Paper Timing
- 90m working plus 5m perusal
- Exam Scope
- Summative Units 3 and 4
- Permitted Aids
- QCAA Data Book and calculator
Equilibrium Graph & Shift Picker
- Single vertical concentration spike on graph→One reactant or product added
- Gas concentrations rise; fixed temperature, amounts→Volume decreased; compare gas mole totals
- Smooth graph change without immediate jump→Check temperature and stated experimental conditions
- Q is smaller than Kc→Net forward shift to right
- Qsp exceeds Ksp after mixing→Precipitate forms in solution
Equilibrium Kc, Q & Ksp Rules
- Dynamic Equilibrium
- Closed system; forward equals reverse
- Kc Expression
- Products over reactants; omit s, l
- Q vs Kc
- Q<Kc forward; Q>Kc reverse
- Volume Decrease
- Shifts to fewer gas moles
- Inert Gas Added
- Constant volume causes no shift
- Kc for a Fixed Reaction
- Only temperature alters Kc value
- Simple AB2 Dissolution
- Ksp=4s³; no other ion sources
- Common-Ion Effect
- Lowers molar solubility; Ksp unchanged
Supporting Quantitative Tools
- Mole Calculations
- n = m/M; c = n/V
- Ideal Gas Law
- Use QCAA R = 8.31PV = nRT
- Kelvin Conversion
- Add 273.15 to Celsius temperature
- Solution Heat
- q = mcΔT; retain signed ΔT
- Idealised Calorimetry Heat Transfer
- Reaction heat = negative solution heat
- Catalyst Effect
- Lowers Ea; Kc and ΔH unchanged
Volumetric Glassware Final Rinse Rule
Deliverers get solution; receivers get deionised water
Burette & pipette: reagent solutionConical flask: deionised waterVolumetric flask: deionised water
Strong Acid vs Concentrated Acid
Strong / Weak
- Measures degree of ionisation
- Strong completely ionises (HCl, HNO3)
- Weak acid partially ionises
Concentrated / Dilute
- Measures solute moles per litre
- Changed by adding water solvent
- Independent of Ka constant
Ionisation extent vs molarity c
Titration Decisions at 298 K
- Strong acid titrated with strong base→Equivalence point pH = 7.00
- Weak acid titrated with strong base→Basic equivalence; half-volume pH matches pKa
- Strong acid titrated with weak base→Equivalence point pH < 7
- Rinsing burette or pipette before use→Rinse with solution it delivers
- Rinsing conical or volumetric flask→Rinse with deionised water only
pH, Kw, Ka/Kb, Buffers & Titrations
- Brønsted-Lowry
- Acid donates H+; base accepts
- Kw at 298 K
- 1.0 × 10⁻¹⁴; pH + pOH 14
- Conjugate Pair Rule
- Ka times Kb equals Kw
- Weak-Acid [H⁺], Small Dissociation
- √(Ka c); validate approximation
- Weak-Acid Half-Equivalence
- [HA] ≈ [A−]; pH ≈ pKa
- Indicator Range
- Changes colour across pKa ± 1
- Pipette & Burette
- Final rinse with delivered solution
- Conical & Vol Flask
- Final rinse with deionised water
KOHES Half-Equation Balancing Order
Key atoms, Oxygen H2O, Hydrogen H+, Electrons, States
K: balance non-O/H atomsO-H: add H2O then H+E-S: balance charge with e-, states
Galvanic Cell vs Electrolytic Cell
Galvanic Cell
- Standard galvanic reaction: E°cell >0
- Chemical to electrical energy
- Anode negative (-); cathode positive (+)
Electrolytic Cell
- Non-spontaneous, driven by DC source
- Electrical to chemical energy
- Anode positive (+); cathode negative (-)
AN OIL RIG holds in both
Aqueous Electrolysis Product Picker
- Cathode: aqueous Na⁺, Mg²⁺ or Al³⁺→Water reduces to H2 and OH-
- Cathode with aqueous Cu²⁺ or Ag⁺→Metal ion reduces to solid metal
- Anode (+): inert electrode with SO4²-/NO3-→Water oxidises to O2 and H+
- Suitable inert anode (+): concentrated aqueous NaCl→Cl- oxidises to Cl2 gas
Redox, Cells & Faraday's Laws
- Oxidation Exceptions
- Peroxide O -1; hydride H -1
- KOHES Half-Equations
- Key, O, H, electrons, states
- Standard Conditions
- 298 K, 100 kPa, 1.0 M
- Standard Cell EMF
- E°cathode minus E°anodeE°cell > 0
- Salt Bridge Flow
- Anions to anode; cations cathode
- Copper Electrorefining
- Blister anode (+); pure cathode (-)
- Electric Charge Q
- Current amps times time secondsQ = It
- Moles of Electrons
- Charge Q divided by 96,485n(e-) = Q/F
Electrode & Redox Direction (AN OIL RIG)
Anode is Oxidation (loss); Cathode is Reduction (gain)
OIL: Oxidation Is Loss of e-RIG: Reduction Is Gain of e-AN OX and RED CAT always
Primary, Secondary, Tertiary Alcohol Oxidation
Primary distils to aldehyde, refluxes to acid; secondary ketone
1° + distil → aldehyde1° + reflux → carboxylic acid2° yields ketone; 3° unreactive
Addition vs Condensation Polymerisation
Addition Polymer
- Alkene monomer double bond opens
- Monomer atoms retained in polymer
- Draw continuation bonds through brackets
Condensation Polymer
- Two reactive groups per monomer
- Small molecules eliminated at links
- Identify ester or amide linkage
Recognise the linkage and recover monomers
Organic Priority, Isomers & Reactions
- Ester Naming
- Alcohol-derived alkyl; acid-derived alkanoate
- Boiling Point Comparisons
- Compare size, branching and intermolecular forces
- Alkane + Br2
- UV light substitution forms haloalkane
- Bromine Water Test
- Alkene decolourises orange Br2 rapidly
- Markovnikov's Rule
- H joins carbon with more H
- 1° Alcohol Oxidation
- Distil for aldehyde; reflux acid
- 2° vs 3° Alcohol
- 2° yields ketone; 3° resists
- Esterification
- Acid + alcohol, conc H2SO4 reflux
Acidic vs Alkaline Ester Hydrolysis
Acidic Hydrolysis
- Dilute H+ catalyst with heat
- Reversible equilibrium reaction
- Forms carboxylic acid + alcohol
Alkaline (Saponification)
- Aqueous NaOH or KOH heat
- Irreversible reaction to completion
- Forms carboxylate salt + alcohol
Reversible acid vs irreversible salt
Polymers, Proteins & Carbohydrates
- Addition Polymer
- C=C opens; monomer atoms retained
- Condensation Polymer
- Small molecules lost when links form
- LDPE vs HDPE
- Branched flexible vs linear crystalline
- Amino Acid Charge
- Below pI positive; above pI negative
- Tripeptide Formation
- Three amino acids; two peptide links
- Disaccharide Formation
- Two monosaccharides; one condensation linkage
- Polymer Hydrolysis
- Break susceptible links using water
Yield vs Atom Economy: Different Scope
Percentage Yield
- Experimental over theoretical times 100%
- Measures actual lab recovery
- Lowered by incomplete or side reactions
Atom Economy
- Stoichiometry-based material efficiency
- Internal SHE in current syllabus
- Not required external-assessment subject matter
External yield; internal SHE atom economy
Organic Evidence Picker
- Broad O–H at 3200–3600 cm⁻¹→Consider alcohol; check remaining evidence
- Acid O–H plus carbonyl absorption→Consider carboxylic acid; compare other data
- Carbonyl without acid O–H→Compare aldehyde, ketone and ester evidence
- Amino acid buffer pH below pI→Positive ion moves toward negative electrode
Synthesis, Yield & Industrial Design
- Percentage Yield
- Experimental over theoretical times 100%
- Multi-Step Yield
- Multiply fractional step yields together
- Atom Economy — Internal SHE
- Stoichiometric efficiency; not 2026 EA requirement
- Haber Process
- Iron catalyst; rate–yield temperature compromise
- Contact Process
- V2O5 catalyst; SO3 absorbed into acid
- Ethanol Fermentation
- C6H12O6 → 2C2H5OH + 2CO2
- Hydrogen Fuel Cell
- Overall: 2H2 + O2 → 2H2O
- Alkaline Fuel-Cell Anode
- 2H2 + 4OH− → 4H2O + 4e−
TLC vs Electrophoresis
TLC
- Different affinities for stationary/mobile phases
- Rf compares migration distances
- Compare under identical conditions
Electrophoresis
- Electrical field moves charged species
- Charge depends on pH versus pI
- Net-zero species migrate little
Solvent affinity versus net electrical charge
IR, MS, Chromatography and Electrophoresis
- IR Alcohol O–H
- 3200–3600 cm⁻¹; use complete spectrum
- IR Acid O–H
- 2500–3000 cm⁻¹ plus carbonyl evidence
- IR Carbonyl C=O
- 1700–1750 cm⁻¹; not unique identification
- MS Molecular Ion
- Intact ion; may be absent
- MS Base Peak
- Most intense; normalised to 100%
- TLC Retention Factor
- Spot distance divided by solvent-front distance
- Electrophoresis Below pI
- Positive amino acid moves toward cathode
- Optical Isomerism
- Chiral carbon: four different attached groups
Common Traps
Subtract Potentials; Scale ΔG°, Not E°
E°: intensive, unchanged by reaction coefficients ≠ ΔG°: extensive, scales with reaction coefficients
Equilibrium Expression: Omitted versus Included Species
Pure solids and liquids: omit ≠ Aqueous and gaseous species: include
Conical Flask Rinse: Water versus Analyte
Water: dilution without extra analyte moles ≠ Analyte: extra moles falsely inflate titre
Warm Pure Water: Neutrality versus Acidity
Above 25°C: pH<7, yet [H⁺]=[OH⁻] ≠ Acidic: [H⁺]>[OH⁻], regardless of temperature
Kc Changes: Fixed Reaction, Fixed Conventions
Temperature change: can alter Kc ≠ Volume/catalyst changes: cannot alter Kc
Ester Naming: Alcohol versus Acid Contributions
Alcohol-derived -yl prefix ≠ Carboxylic-acid-derived -oate suffix
Last Minute
- 1.External assessment contributes 50%
- 2.Each paper: 90 working, 5 perusal
- 3.Use current QCAA data-book constants
- 4.State assumptions in equilibrium calculations
- 5.Indicator end point differs from equivalence
- 6.Check conductometric graph slope changes
- 7.E°cell: subtract tabulated reduction potentials
- 8.Faraday: q = It = n(e−)F
- 9.Balance fuel-cell half-equations and charges
- 10.TLC: spot distance / solvent distance
- 11.Below pI: migrate toward cathode
- 12.Compare whole spectra; avoid single-peak guesses
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