S5 Chemistry | Alcohols, Carboxylic Acids and Esters: Lesson-Plan Guide

S5 Chemistry | Alcohols, Carboxylic Acids and Esters: Lesson-Plan Guide | 60 minutes from structure to calculation

2026-11-06

Tutor lesson-prep guides · Secondary Chemistry

Students see C2H5OH and CH3COOH as two oxygen-containing carbon compounds and then guess at every test question. Three questions separate them: is there a C=O, is there an O-H, and which carbon carries the O-H. Once those are settled, oxidation, esterification and tests all follow.

Objectives — Students can: (1) identify a primary alcohol, a carboxylic acid and an ester from a displayed formula and name the functional group; (2) write the two-step oxidation of a primary alcohol with reagents and colour change; (3) distinguish a carboxylic acid with the hydrogencarbonate test and calculate an ester yield, getting both calculations fully right.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Functional groups	What is the C=O group called	Carbonyl
Redox	Does oxidation gain or lose electrons	Lose electrons
Moles and mass	What is the mass of 0.10 mol of ethanol, Mr 46	4.6 g
Homologous series	How do methanol and ethanol differ	By one CH2 unit

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0-15 min	Three structures side by side	Give C2H5OH, CH3COOH and CH3COOC2H5; students circle the functional groups and state the difference	Circle O-H and C=O positions
15-28 min	Two-step oxidation	Model primary alcohol to aldehyde to acid with acidified dichromate and the orange-to-green change	Write both equations with observations
28-38 min	Testing the acid	Model the hydrogencarbonate fizz, the carbonate test and ester formation	Predict results for four test tubes
38-50 min	Esterification and yield	Model the reversible reaction, concentrated sulfuric acid, and yield as actual over theoretical for 0.10 mol at 68 per cent	Calculate 5.98 g with units
50-57 min	Why yield is below 100 per cent	Discuss reversibility, evaporation and transfer loss	Write three reasons
57-60 min	Exit check	Three quick questions on groups, reagents, yield	Answer independently

03 Teaching script (read it out)

Scene 1: Three questions sort the three groups

First: is there a C=O. If not, it is an alcohol or an ether. Second: is there an O-H. An O-H on a chain-end carbon means a primary alcohol; an O-H on the same carbon as the C=O means a carboxylic acid. Third: what sits beside the C=O, a hydrogen, a carbon or an oxygen. Oxygen means an ester.
Draw all three questions on one sheet so students can eliminate their way to the answer instead of memorising names.

Students do: answer yes or no to the three questions for six structures, then name each functional group.

Scene 2: Oxidation needs reagents and colour, not just the word

Primary alcohols oxidise with acidified potassium dichromate, orange to green; the aldehyde can oxidise further to the acid. Secondary alcohols give ketones; tertiary alcohols do not oxidise, which is the most missed point.
Put the three alcohols side by side and ask which one has two hydrogens on the carbon carrying the O-H. Only the primary one does, so only it reaches an aldehyde. Students should say the colour change aloud, because that is the mark in practical questions.

Students say: why a tertiary alcohol does not oxidise, answering that its O-H carbon carries no hydrogen.

Scene 3: Yield runs from mole ratio to mass

Esterification is an equilibrium, so yield never reaches 100 per cent. The question usually gives moles of alcohol and a yield and asks for the mass of ester. Steps: balanced equation, one-to-one ratio, theoretical moles, multiply by yield, multiply by the Mr of the ester.
For 0.10 mol ethanol at 68 per cent with ethyl ethanoate Mr 88, that is 0.068 mol and 5.98 g. The commonest slip is multiplying the yield after converting to mass, or counting water in the product mass.

Students do: redo the calculation for 0.25 mol ethanol at 55 per cent, writing every unit.

04 Question types and worked steps

Type	Example	Steps	Answer
Identify the group	What class is CH3CH(OH)CH3	O-H present, no C=O, OH on a middle carbon, so secondary	Propan-2-ol, a secondary alcohol
Oxidation	The two products of oxidising a primary alcohol	Aldehyde then acid, with reagent and colour	Aldehyde to acid, orange to green
Acid test	How to tell ethanoic acid from ethanol	Add hydrogencarbonate; the acid fizzes	Acid fizzes, ethanol does not
Ester yield	Mass of ester from 0.10 mol ethanol at 68 per cent	One-to-one ratio, apply yield, multiply by Mr 88	5.98 g

Sanity check (teach this): Reasonableness checks: every answer must name the functional group, not just the compound; oxidation must state reagent and colour change; the ester equation needs a reversible arrow and concentrated sulfuric acid; yield cannot exceed 100 per cent; masses carry grams; a catalyst is never counted as a reactant in mole calculations; test answers must give an observation such as fizzing, not simply that it reacts.

05 Independent practice (3 questions)

Question	Answer	What to watch
Sort six structures	Walk the three questions and name each group	Check elimination rather than memory
Two oxidation equations	Include reagent, condition and colour	Check for the missing acid or colour
Two yield questions	One for mass, one for percentage yield	Check mole ratio and units

06 Common mistakes and what to say

Mistake	Student writes	Say this
Oxidising a secondary alcohol to an aldehyde	Propan-2-ol oxidises to propanal	That carbon carries one hydrogen, so oxidation stops at the ketone, not the aldehyde.
Writing that it reacts	Adding hydrogencarbonate gives a reaction	Write the observation: bubbles of carbon dioxide. No observation, no mark.
Applying yield in the wrong place	Multiplying 68 per cent after converting to mass	Apply the yield to the moles first, then multiply by the Mr. Any other order gives the wrong number.
Forgetting the equilibrium	A single arrow and a yield of 100 per cent	Esterification is an equilibrium, so it needs a reversible arrow. A hundred per cent means yield is not understood.

07 Homework (paper, section and question numbers)

Secondary Chemistry chapter index — All chapters in this subject
Lesson-plan guides index — Matching chapters in other subjects
Redo this chapter — Redo the six structures and both yield calculations

08 Exit check (last 5 minutes)

Question	Answer	Decision
The group only acids have	C=O and O-H on the same carbon	Answering only O-H means act one again
Second oxidation product of a primary alcohol	A carboxylic acid	Answering aldehyde means act two again
Percentage yield formula	Actual over theoretical times 100	Answering actual over reactant means act three again
Hydrogencarbonate observation	Bubbles of carbon dioxide	Answering a colour change means act two again

09 Tutor FAQ

Do students need infrared data?

The syllabus only needs the typical absorption regions; reactions and calculations carry the marks.

Why concentrated sulfuric acid?

It catalyses and absorbs water, shifting the equilibrium right; both points are needed.

Can a yield exceed 100 per cent?

Not in practice; a result above 100 per cent usually means impurities or incomplete drying.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.