DSE Chemistry: Acids and Bases — Tutor Lesson Plan (pH, neutralisation, titration)

2026-10-27

Tutor lesson-prep guides · Secondary chemistry

Titration marks are lost in the unit conversion, not the formula. Drill one move: turn cm3 into dm3, then multiply by concentration.

Objectives — the student can define acids and bases, compute pH from concentration, and complete neutralisation calculations using mole ratios.

01 Prerequisites (3-minute check)

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

Skill	Quick check	Pass mark
Moles	How many cm3 in 1 dm3?	1000
Concentration	What does 0.1 M mean?	0.1 mol per dm3
Logarithms	Negative log of 10 to the minus 2	2

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0-10 min	Definitions	Proton donor and acceptor	Four examples
10-24 min	pH and indicators	pH = -log[H+]	Three values
24-40 min	Neutralisation	H+ plus OH- gives water	Three equations
40-54 min	Titration	Mole ratio and concentration	Two calculations
54-57 min	Format	Equation first, then moles	Rewrite one
57-60 min	Exit check	Three questions marked	Finish alone

03 Teaching script (read it out)

Scene 1: Acids donate, bases accept

Hydrochloric and sulfuric acid are strong; sodium hydroxide is a strong base; ammonia is weak.
Strong acids ionise fully, weak acids partly, so equal concentrations give different pH.

Student states which has the lower pH: 0.1 M HCl or 0.1 M ethanoic acid.

Scene 2: pH only reads hydrogen ion concentration

pH = -log[H+]. A 0.01 M strong acid has pH 2.
Each unit is a tenfold change, so diluting tenfold raises pH by about 1.

Student computes the pH of 0.001 M HCl: 3.

Scene 3: Titration: the equation gives the ratio

HCl + NaOH gives NaCl + water, one to one.
0.1 M HCl, 25 cm3, is 0.0025 mol, needing 25 cm3 of 0.1 M NaOH.
With sulfuric acid and two hydroxides the ratio is one to two, so double the base.

Note: write the equation before touching the numbers.

04 Question types and worked steps

Type	Example	Steps	Answer
pH	0.01 M HCl	pH = -log(0.01)	2
Neutralisation volume	0.1 M HCl 25 cm3 with 0.1 M NaOH	One to one	25 cm3
Mole ratio	H2SO4 with NaOH	One to two	Double the base
Indicator	Strong acid with strong base	Phenolphthalein, colourless to pink	End point near pH 7

Sanity check (teach this): For a one-to-one titration the moles of acid must equal the moles of base; a factor of two means the ratio was ignored.

05 Independent practice (3 questions)

Question	Answer	What to watch
pH of 0.001 M HCl	3	Negative log of 10 to the minus 3
0.05 M NaOH 25 cm3 needs how much 0.1 M HCl	12.5 cm3	One to one ratio
pH after tenfold dilution	Rises by 1	Concentration falls tenfold

06 Common mistakes and what to say

Mistake	Student writes	Say this
Multiplying cm3 by concentration directly	skips dm3	Divide by 1000 first.
Ignoring the equation ratio	treats sulfuric acid as one to one	Count the hydrogen ions.
Reading pH as concentration	says pH 2 means 2 M	pH is a negative logarithm.
Wrong indicator	methyl orange for strong acid and base	Phenolphthalein is standard.

07 Homework (paper, section and question numbers)

Secondary chemistry chapter index — Use the three questions on this page

08 Exit check (last 5 minutes)

Question	Answer	Decision
pH of 0.001 M HCl	3	All right: move to redox
0.05 M NaOH 25 cm3 with 0.1 M HCl	12.5 cm3	One wrong: re-teach moles
pH after tenfold dilution	Rises by 1	Two wrong: repeat scene 3

09 Tutor FAQ

Memorise strong acids?

Hydrochloric, sulfuric, nitric; and two strong bases.

Weak acid pH?

Compare only for DSE.

Titration errors?

Rinsing, reading the burette, indicator choice.

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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.