S5 Chemistry: Ionic Precipitation (Paper 1: Basics)

2026-11-12

Ten items on the groundwork of precipitation: what a precipitate is, solubility rules, formation of silver chloride and barium sulphate, and basic mole and mass arithmetic, with answers.

Direct answers　Answers in order: an insoluble solid forms, white silver chloride, all soluble, Ag+ plus Cl- gives AgCl(s), barium sulphate, 0.0025 mol, 0.359 g, 2.33 g, every combination is soluble, spectator ions should not be included.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	20
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: S5 Chemistry: Ionic Precipitation
Level	S5

02　Questions (10 items)

FoundationWhat is a precipitation reaction?
FoundationWhat colour is the precipitate when silver nitrate solution is added to sodium chloride solution?
FoundationHow soluble in water are sodium, potassium, ammonium and nitrate salts?
IntermediateWrite the net ionic equation for silver nitrate solution reacting with sodium chloride solution.
IntermediateWhat is the white precipitate formed when barium chloride solution is added to sodium sulphate solution?
IntermediateHow many moles of silver chloride form when 25.0 cm3 of 0.100 M silver nitrate reacts with excess sodium chloride?
ChallengeFrom the previous question, what mass of silver chloride is obtained, given Mr = 143.5?
ChallengeWhat mass of barium sulphate, Mr = 233, forms when 50.0 cm3 of 0.200 M barium chloride reacts with excess sodium sulphate?
ChallengeWhy does no precipitate form when potassium nitrate solution is mixed with sodium chloride solution?
Error redoA student includes sodium and nitrate ions in a net ionic equation. What is wrong?

03　Answers and one-line notes

#	Answer	One-line note
1	Two solutions are mixed and an insoluble solid, called a precipitate, is formed.	The reaction is an exchange of ions with no electron transfer, so it is not a redox reaction.
2	A white precipitate of silver chloride.	Silver ions combine with chloride ions to give insoluble silver chloride, the classic test for chloride.
3	They are all soluble in water.	These salts have relatively low lattice energies so hydration pulls them into solution; they are therefore often spectator ions.
4	Ag+(aq) + Cl-(aq) -> AgCl(s)	A net ionic equation shows only the ions that actually change; sodium and nitrate ions are spectators.
5	Barium sulphate.	Barium ions and sulphate ions give very insoluble barium sulphate, the standard test for sulphate.
6	0.0025 mol	Moles equal concentration times volume in dm3, and silver ions give silver chloride in a one to one ratio.
7	0.359 g	Mass is moles times molar mass, 0.0025 times 143.5 gives 0.35875, rounded to three significant figures.
8	2.33 g	There is 0.0100 mol of barium ions, giving the same moles of barium sulphate, which is 2.33 g.
9	Because every possible combination of these ions is soluble, so no insoluble solid can form.	A precipitate needs an insoluble product; all four ion combinations here are soluble, so the mixture stays clear.
10	A net ionic equation should show only the ions that actually react; sodium and nitrate are spectator ions.	Spectator ions are unchanged before and after the reaction, so including them defeats the purpose of a net equation.

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.

Write the three solubility exceptions once each – silver chloride, barium sulphate, calcium carbonate – and note the colour of each.Tutor Registration →

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