How do the end point and the equivalence point differ?

The equivalence point is exact neutralisation by mole ratio, while the end point is where the indicator changes colour.

Why is a conical flask used rather than a beaker?

Its narrow neck limits splashing during swirling and makes the colour change easy to see.

Why does a carbonate titration have two stages?

The carbonate first becomes hydrogencarbonate and then carbon dioxide and water, each stage taking the same moles of acid.

Do equal concentrations always need equal volumes?

No, the mole ratio in the equation decides, and a dibasic acid needs twice the moles of alkali.

S5 Chemistry titration paper 1: molarity and neutralisation calculations

2026-11-10

Tutor Prep Guide · S5 Chemistry Acid-Base Titration

Ten items start from molarity and the neutralisation ratio, then cover dilution, indicator choice and the end point.

Direct answers　Items 01 to 03 cover the mole ratio in neutralisation, 04 to 06 molarity and dilution, 07 to 09 indicators and the end point, and 10 the slip over the two hydrogen ions of sulphuric acid.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	25
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: S5 Chemistry Acid-Base Titration
Level	S5

02　Questions (10 items)

FoundationSodium hydroxide solution of 0.100 M is used to titrate 25.0 cm3 of 0.100 M hydrochloric acid. What volume of alkali is needed?
FoundationWhat volume of 0.100 M sodium hydroxide neutralises 20.0 cm3 of 0.200 M hydrochloric acid?
FoundationWhat volume of 0.200 M sodium hydroxide neutralises 25.0 cm3 of 0.100 M sulphuric acid?
IntermediateA solution of 250 cm3 contains 0.050 mol of solute. Find its molarity.
IntermediateDissolve 2.0 g of sodium hydroxide, of molar mass 40.0, in water to make 500 cm3 of solution. Find the molarity.
IntermediateDilute 20.0 cm3 of 0.500 M hydrochloric acid to 100 cm3 with water. Find the new concentration.
ChallengeSodium hydroxide is used to titrate hydrochloric acid with phenolphthalein as indicator. How does the colour change at the end point?
ChallengeWhich indicator suits the titration of ammonia solution with hydrochloric acid?
ChallengeAt the end point of a titration, how are the acid and the alkali related?
Error redoA student titrates 25.0 cm3 of 0.100 M sulphuric acid with 0.100 M sodium hydroxide and answers 25.0 cm3. What is the correct volume?

03　Answers and one-line notes

#	Answer	One-line note
1	25.0 cm3	The acid and the alkali react one to one, so equal concentrations need equal volumes.
2	40.0 cm3	The acid contains 0.200 times 0.0200, which is 0.00400 mol, divided by 0.100 M.
3	25.0 cm3	Each mole of sulphuric acid supplies two hydrogen ions, so 0.00500 mol of hydroxide is needed.
4	0.200 M	Molarity is moles divided by volume in dm3, that is 0.050 divided by 0.250.
5	0.100 M	2.0 g is 0.050 mol, which is then divided by 0.500 dm3.
6	0.100 M	The number of moles stays at 0.0100 mol but now fills 0.100 dm3.
7	From colourless to pink	Phenolphthalein is colourless in acid and pink in alkali.
8	Methyl orange	The equivalence point of a strong acid with a weak base is acidic, and methyl orange changes colour in acid.
9	The moles of hydrogen ions equal the moles of hydroxide ions	At the end point the moles of H plus match the moles of OH minus in the equation ratio.
10	50.0 cm3	Sulphuric acid has two replaceable hydrogen ions, so twice as many moles of alkali are needed.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

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