What does HSC Chemistry Module 7 cover?

Module 7 (Organic Chemistry) covers naming and structures of organic compounds (alkanes, alkenes, alkynes, alcohols, aldehydes, ketones, carboxylic acids, esters, amines), reactions including substitution, addition, oxidation, esterification, polymerisation, and applications like biofuels, polymers, and pharmaceuticals. Approximately a quarter to a third of total marks in recent papers (NESA does not publish a fixed module weighting).

What are the main functional groups in HSC organic chemistry?

Alkanes (C-C, C-H single bonds), alkenes (C=C double bond), alkynes (C triple bond C), alcohols (-OH), aldehydes (-CHO), ketones (-C(=O)-), carboxylic acids (-COOH), esters (-COO-), amines (-NH2). Each has characteristic reactions. Memorise the functional group shapes and one named example per category.

How do I name organic compounds in HSC Chemistry?

IUPAC nomenclature - identify the longest carbon chain (gives the prefix - meth, eth, prop, but, pent), identify the functional group (gives the suffix - ane, ene, ol, al, one, oic acid, oate, amine), and number from the end nearest the highest-priority functional group. Examples - butan-2-ol, propanoic acid, ethyl ethanoate.

What are the main reaction types in HSC organic chemistry?

Substitution (alkane to halogenoalkane with halogens), addition (alkene plus H2/X2/HX/H2O), oxidation (alcohol to aldehyde/ketone/carboxylic acid), esterification (carboxylic acid plus alcohol to ester plus water), polymerisation (addition or condensation), combustion (organic to CO2 plus water). Know the reagents and conditions for each.

How are polymers covered in HSC Chemistry?

HSC covers two main polymer types. Addition polymers form from alkene monomers via opening of the double bond (e.g. polyethylene from ethene, polystyrene from styrene). Condensation polymers form when monomers join with loss of a small molecule like water (e.g. polyester from diol plus dicarboxylic acid, nylon from diamine plus dicarboxylic acid).

How is organic chemistry examined?

Common patterns - identify a compound from its structural formula and name it (or vice versa), predict the products of a given reaction, propose a synthesis route from one compound to another (potentially multi-step), interpret IR/NMR/mass spectra to identify an unknown, evaluate environmental or social implications of a polymer or pharmaceutical.

NSWChemistry

HSC Chemistry organic chemistry (Module 7): 2026 guide

A complete guide to HSC Chemistry Module 7 (Organic Chemistry). Naming, functional groups, reaction types, polymer chemistry, and the patterns markers expect.

Generated by Claude Opus 4.817 min readNESA-CHEM-MOD-7Updated 2026-05-25

Reviewed by: AI editorial process; not yet individually human-reviewed

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What Module 7 asks
Functional groups
Naming organic compounds (IUPAC)
Reaction types
Hydrocarbons as fuels
Common HSC Module 7 traps
How Module 7 is examined
Practice strategy
Check your knowledge

What Module 7 asks

HSC Chemistry Module 7 (Organic Chemistry) is the most memorisation-heavy module in the course, typically accounting for a substantial share of marks in recent papers (NESA does not publish fixed module weightings). Students who treat organic as a system of named functional groups and predictable reactions do well; students who try to derive everything from first principles run out of time.

The content is structured around functional groups and the reactions that interconvert them.

Functional groups

Memorise these. Strong students can draw each from memory in under 5 seconds.

Group	Structure	General formula	Suffix
Alkane	C-C, C-H single bonds	$C_nH_{2n+2}$	-ane
Alkene	C=C double bond	$C_nH_{2n}$	-ene
Alkyne	C≡C triple bond	$C_nH_{2n-2}$	-yne
Alcohol	C-OH	$C_nH_{2n+1}OH$	-ol
Aldehyde	-CHO (carbonyl at end)	$C_nH_{2n}O$	-al
Ketone	-C(=O)- (carbonyl middle)	$C_nH_{2n}O$	-one
Carboxylic acid	-COOH	$C_nH_{2n}O_2$	-oic acid
Ester	-COO-	derived	-oate
Amine	-NH2 (or -NHR, -NR2)	$C_nH_{2n+1}NH_2$	-amine

Naming organic compounds (IUPAC)

The rules:

Identify the longest carbon chain containing the highest-priority functional group. The chain length gives the prefix: meth (1), eth (2), prop (3), but (4), pent (5), hex (6), hept (7), oct (8).
Number the carbons from the end nearest the highest-priority functional group.
Add the appropriate suffix and locant (number) for the main functional group.
Identify substituents (methyl, ethyl, halogen, etc.) and add as prefixes with locants.

Worked example: name CH3-CH(OH)-CH2-CH3.

Longest chain: 4 carbons (butane).
Functional group: OH (alcohol, suffix -ol).
Numbering: closest to OH, so the OH carbon is 2.
Name: butan-2-ol.

Worked example: name CH3-COOCH2CH3.

The compound is an ester (CH3-COO-CH2CH3).
The acyl part (left of -COO-) is from ethanoic acid: name the alkyl part attached to the oxygen first (ethyl), then the acyl part (ethanoate).
Name: ethyl ethanoate.

Reaction types

Substitution

Alkanes + halogens (Cl2, Br2) in the presence of UV light yield haloalkanes:

CH_4 + Cl_2 \xrightarrow{UV} CH_3Cl + HCl

Mechanism is free-radical. Reactivity: F > Cl > Br > I.

SN2 of hydroxide with bromoethane: two curly arrows (lone pair to carbon, bond to leaving group) capture the concerted electron flow that gives Walden inversion.

Addition

Alkenes (and alkynes) undergo addition. The double bond opens and reagent adds across the carbons.

Hydrogenation: alkene + H2 (with Ni catalyst) → alkane.
Halogenation: alkene + Br2 → 1,2-dibromoalkane.
Hydration: alkene + H2O (with H2SO4 catalyst) → alcohol.
Hydrohalogenation: alkene + HX → haloalkane (Markovnikov's rule: H goes to the carbon with more H, X to the carbon with fewer H).

Worked example:

CH_2=CH_2 + H_2O \xrightarrow{H_2SO_4} CH_3CH_2OH

HBr plus propene: ionic addition follows Markovnikov to give 2-bromopropane; peroxide-initiated radical addition reverses the regioselectivity and gives 1-bromopropane.

Oxidation

Alcohols are oxidised to aldehydes (primary alcohol with limited oxidiser) or ketones (secondary alcohol). Further oxidation of an aldehyde gives a carboxylic acid.

Common oxidising agents: KMnO4 (potassium permanganate), K2Cr2O7 (potassium dichromate).

CH_3CH_2OH \xrightarrow{KMnO_4} CH_3CHO \xrightarrow{KMnO_4} CH_3COOH

(ethanol → ethanal → ethanoic acid)

Tertiary alcohols (no H on the carbon bearing OH) cannot be oxidised by these reagents.

Esterification

A carboxylic acid plus an alcohol, with H2SO4 catalyst, produces an ester plus water:

CH_3COOH + CH_3CH_2OH \xrightleftharpoons[H_2SO_4]{} CH_3COOCH_2CH_3 + H_2O

(ethanoic acid + ethanol → ethyl ethanoate + water)

This is a reversible reaction at equilibrium. Excess of one reagent (or removal of water) shifts the equilibrium toward the ester.

Esters give characteristic fruity smells (banana, pineapple, pear) and are used in fragrances and flavourings.

Esterification energy profile: activation energy Ea spans reactants to the tetrahedral TS dagger, and the small positive delta H reflects the equilibrium lying close to the reactants in the absence of dehydrating conditions.

Polymerisation

Addition polymerisation: alkene monomers join via opening of the C=C double bond. No small molecule is lost.

n \cdot CH_2=CH_2 \rightarrow -(CH_2-CH_2)_n-

Common addition polymers: polyethylene (from ethene), polypropylene (from propene), polyvinyl chloride (from chloroethene), polystyrene (from styrene).

Condensation polymerisation: monomers join with loss of a small molecule (usually water). Requires monomers with two reactive functional groups each.

Examples:

Polyester (e.g. PET): diol + dicarboxylic acid → polyester + water.
Nylon (e.g. nylon-6,6): diamine + dicarboxylic acid → polyamide + water.

Hydrocarbons as fuels

Combustion of hydrocarbons:

Complete combustion (sufficient oxygen): $C_nH_m + (n + m/4) O_2 \rightarrow n CO_2 + m/2 H_2O$ . Produces only CO2 and water.

Incomplete combustion (insufficient oxygen): produces CO (toxic) and/or soot (carbon particles).

Biofuels include bioethanol (from fermentation of sugars), biodiesel (from transesterification of vegetable oils). Strong responses evaluate the trade-offs - reduced fossil fuel use vs land use, ethical and economic concerns.

Common HSC Module 7 traps

Confusing aldehydes and ketones: Aldehyde has the -CHO at the end of the chain. Ketone has -C(=O)- in the middle. Different naming, different reactivity (aldehydes can be oxidised further; ketones cannot).
Forgetting Markovnikov's rule: For asymmetric alkenes plus HX, the H adds to the carbon with MORE H atoms; the X adds to the carbon with FEWER H atoms. This is the major product.
Naming errors with locants: Always number from the end nearest the highest-priority functional group. If both ends give the same locant for the main group, choose the numbering that gives lower locants to substituents.
Mixing up addition and condensation polymerisation: Addition: no small molecule lost. Condensation: water (or similar) released per bond formed.
Forgetting the H2SO4 catalyst in esterification: Many students write the reaction without the catalyst. Markers may not award the mark.

How Module 7 is examined

In the HSC Chemistry exam:

Multiple choice. Identify a compound from its structure. Name an organic compound. Predict products of a reaction.
Section II short questions (3-5 marks). Draw a structural formula. Write a balanced equation for a reaction. Identify functional groups.
Section II extended response (6-9 marks). Multi-step synthesis (e.g. propose a route from ethene to ethyl ethanoate). Spectra interpretation. Polymer evaluation.

Practice strategy

For HSC Chemistry Module 7:

Term 3. Memorise functional groups and the standard reactions cold. Draw each from memory.
Term 4. Past papers focused on Module 7. Multi-step synthesis questions repeat patterns; spot them.

Build a flowchart of how the functional groups interconvert (alkene → alcohol → aldehyde → carboxylic acid; carboxylic acid + alcohol → ester). This single diagram answers most of the synthesis questions.

Check your knowledge

A mix of definitional, calculation/explanation, and exam-style multi-part questions covering this topic. Aim to answer all under exam conditions, then check against the solutions block.

Define the term structural isomer and draw the three structural isomers of $C_4H_{10}O$ that are alcohols, naming each using IUPAC nomenclature. (4 marks)
(a) Write the balanced equation for the complete combustion of octane ( $C_8H_{18}$ ), a major component of Australian unleaded petrol. (b) Calculate the volume of $CO_2$ at standard laboratory conditions (25 degrees C, 100 kPa, $V_m = 24.79$ L mol $^{-1}$ ) produced when 5.00 L of liquid octane (density 0.703 g mL $^{-1}$ , $M = 114.23$ g mol $^{-1}$ ) is combusted. (5 marks)
The reaction $CH_3CH_2OH + CH_3COOH \rightleftharpoons CH_3COOCH_2CH_3 + H_2O$ is set up by mixing 0.100 mol ethanol with 0.100 mol ethanoic acid plus a few drops of concentrated $H_2SO_4$ in a sealed 1.00 L vessel. At equilibrium the vessel contains 0.667 mol ethyl ethanoate. (a) Calculate $K_c$ . (b) State two ways the yield could be increased and justify each using Le Chatelier's principle. (c) Explain the role of the $H_2SO_4$ . (6 marks)
Predict the major organic product of each of the following reactions, naming it and identifying the reaction type. (a) But-2-ene + HBr. (b) Propan-2-ol heated under reflux with acidified $K_2Cr_2O_7$ . (c) Propan-1-ol + ethanoic acid with conc. $H_2SO_4$ . (d) Ethene + steam at 300 degrees C with phosphoric acid catalyst. (8 marks)
(a, 3) Distinguish addition polymerisation from condensation polymerisation, with a balanced equation showing one repeat unit for polyethylene and one repeat unit for nylon-6,6 (formed from hexamethylenediamine and hexanedioic acid). (b, 3) Compare the chemical recyclability of these two polymers, justifying with reference to bond types. (c, 2) Identify one Australian context where condensation polymers have replaced traditional materials. (8 marks)
Compound X has the molecular formula $C_3H_6O$ and reduces acidified $K_2Cr_2O_7$ from orange to green. Compound Y has the same formula but does not react. (a) Identify a possible identity for X and Y. (b) Draw their structural formulas. (c) Write a balanced equation for the oxidation of X by acidified dichromate, generating a carboxylic acid. (5 marks)
Compare and contrast the substitution of chlorine with methane (under UV) and the addition of chlorine with ethene (in the dark). Address (a) the mechanism, (b) the structural feature in each hydrocarbon that determines the reaction type, and (c) the product mixture. (6 marks)
Australia produces approximately 9 billion litres of bioethanol annually from sugar-cane residue. (a) Write the balanced equation for fermentation of glucose to ethanol. (b) Discuss the renewability of bioethanol compared with fossil-derived ethanol (produced from petrochemical ethene plus water), referring to feedstock, $CO_2$ life-cycle, and land-use. (c) Evaluate the use of bioethanol-petrol blends (e.g. E10) as a transport fuel in Australia, addressing engine compatibility, emissions and Indigenous land-use considerations. Write a coherent extended response of approximately 200 to 300 words. (7 marks)

Solutions

Q1: Structural isomers have the same molecular formula but different connectivity. For $C_4H_{10}O$ , the three alcohols are: butan-1-ol ( $CH_3CH_2CH_2CH_2OH$ , primary), butan-2-ol ( $CH_3CH(OH)CH_2CH_3$ , secondary), and 2-methylpropan-2-ol ( $(CH_3)_3COH$ , tertiary). A fourth alcohol exists as 2-methylpropan-1-ol ( $(CH_3)_2CHCH_2OH$ , primary); markers reward any three correctly drawn and named.
Q2: (a) $2C_8H_{18} + 25O_2 \rightarrow 16CO_2 + 18H_2O$ . (b) Step 1: mass octane $= 5000 \times 0.703 = 3515$ g. Step 2: moles octane $= 3515 / 114.23 = 30.77$ mol. Step 3: moles $CO_2 = 30.77 \times 8 = 246.2$ mol. Step 4: volume $CO_2 = 246.2 \times 24.79 = 6105$ L $\approx 6.10 \times 10^3$ L.
Q3: (a) At equilibrium: $[ester] = [water] = 0.0667$ M; $[acid] = [alcohol] = 0.100 - 0.0667 = 0.0333$ M. $K_c = (0.0667 \times 0.0667) / (0.0333 \times 0.0333) = 4.01$ . (b) Increase yield by (i) adding excess of one reactant (e.g. ethanol), shifting equilibrium to products; (ii) removing water (e.g. with a Dean-Stark trap), pulling equilibrium to the right. Both apply Le Chatelier's principle. (c) Concentrated $H_2SO_4$ catalyses esterification by protonating the carboxylic acid carbonyl, increasing electrophilicity for nucleophilic attack by the alcohol; it also dehydrates the reaction mixture, removing water and shifting equilibrium toward ester.
Q4: (a) But-2-ene + HBr: 2-bromobutane (Markovnikov adds H and Br across symmetric alkene gives one major product). Addition. (b) Propan-2-ol with hot acidified dichromate: propanone (secondary alcohol oxidises to ketone; further oxidation requires stronger conditions). Oxidation. (c) Propan-1-ol + ethanoic acid with $H_2SO_4$ : propyl ethanoate plus water. Esterification (condensation). (d) Ethene + steam with $H_3PO_4$ catalyst: ethanol. Hydration (addition).
Q5: (a) Addition polymerisation: $n CH_2{=}CH_2 \rightarrow {-}(CH_2{-}CH_2){-}_n$ (polyethylene). No small molecule is lost; the C=C bond opens to form a saturated backbone. Condensation polymerisation: $n H_2N(CH_2)_6NH_2 + n HOOC(CH_2)_4COOH \rightarrow {-}[HN(CH_2)_6NHCO(CH_2)_4CO]{-}_n + 2n H_2O$ (nylon-6,6). Each amide bond formation releases water. (b) Polyethylene is connected by non-polar C-C bonds, which are kinetically inert to hydrolysis, so polyethylene cannot be chemically depolymerised under mild conditions and is typically mechanically recycled or incinerated. Nylon-6,6 contains amide bonds that can be hydrolysed under acidic or basic conditions to regenerate the monomers (chemical recycling), although in practice this is energy-intensive. (c) Polyethylene terephthalate (PET) bottles have replaced glass for soft-drink packaging in Australia; PET is a condensation polyester recyclable into new bottles or polyester fabric.
Q6: (a) X is a primary alcohol (propan-1-ol) or aldehyde (propanal) that reduces dichromate; Y is a ketone (propanone) that does not react with $K_2Cr_2O_7$ . The most likely identities consistent with both having $C_3H_6O$ are X = propanal and Y = propanone (since propan-1-ol is $C_3H_8O$ , not $C_3H_6O$ ). (b) X = $CH_3CH_2CHO$ ; Y = $CH_3COCH_3$ . (c) $3CH_3CH_2CHO + Cr_2O_7^{2-} + 8H^+ \rightarrow 3CH_3CH_2COOH + 2Cr^{3+} + 4H_2O$ .
Q7: (a) Methane + chlorine under UV proceeds by a free-radical chain mechanism (initiation: $Cl_2 \rightarrow 2Cl\cdot$ by UV; propagation: $Cl\cdot + CH_4 \rightarrow CH_3\cdot + HCl$ , $CH_3\cdot + Cl_2 \rightarrow CH_3Cl + Cl\cdot$ ). Ethene + chlorine in the dark proceeds by electrophilic addition through a chloronium intermediate (no radicals; reacts at room temperature without UV). (b) Methane has only single C-H and C-C bonds (saturated), so the only available reaction is substitution of a C-H. Ethene has a $\pi$ -electron-rich C=C double bond that attacks the electrophilic $Cl_2$ , opening the bond for addition. (c) Substitution gives a statistical mixture (chloromethane, dichloromethane, trichloromethane, tetrachloromethane) since each successive Cl substitution is also activated by UV. Addition gives essentially a single product (1,2-dichloroethane) because once the double bond is consumed, no further reaction occurs.
Q8: (a) $C_6H_{12}O_{6(aq)} \xrightarrow{\text{yeast}} 2C_2H_5OH_{(aq)} + 2CO_{2(g)}$ . (b) Bioethanol is renewable: sugar-cane is regrown each season and the $CO_2$ released on combustion approximately equals that fixed by photosynthesis, giving a near-neutral carbon life-cycle. Fossil-derived ethanol uses non-renewable petrochemical feedstock (ethene from cracking natural gas or oil), so its combustion releases sequestered carbon. Land-use trade-offs include displacement of food crops, water demand, and soil nutrient depletion; in Queensland, sugar-cane residue (bagasse) is often co-fired in mills, partially offsetting these concerns. (c) E10 fuel (10 percent ethanol) is approved for most post-1986 Australian vehicles; older engines or carburettors may suffer corrosion due to ethanol's polar nature. Tailpipe emissions of $CO$ and particulate matter are reduced, but NOx may rise slightly due to higher combustion temperatures. Indigenous land-use considerations include the Wet Tropics and Murray-Darling agricultural regions where cane expansion can conflict with cultural-heritage sites and water-extraction rights, requiring consultation with Traditional Owners and adherence to the Native Title Act. Overall, E10 offers a modest reduction in $CO_2$ life-cycle emissions compared with neat petrol, but is best deployed alongside electrification and improved public transport for a deeper decarbonisation pathway.