S2 Science: Separating Mixtures (Paper 1 (basics))

2026-11-14

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Tutor Prep Guide · Filtration, distillation, fractional distillation and chromatography with Rf calculations

This paper builds the basics: mixtures against pure substances, the uses of filtration and evaporation, distillation by boiling point, and the mobile phase and Rf value in chromatography.

Direct answers　Ask first whether the substance dissolves in water and then whether the boiling points differ, because most answers follow from those two questions. For apparatus questions remember three positions: paper below the funnel rim, thermometer at the side arm, and cooling water in at the bottom and out at the top.

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: S2 Science: Separating Mixtures
Level	S2

02　Questions (10 items)

FoundationSand is mixed with water. Which method separates the sand?
FoundationSalt has dissolved in water. Can filtration separate the salt?
FoundationWhich difference between components does distillation use?
IntermediateSalt solution is evaporated to dryness in an evaporating dish. What is left?
IntermediateIn chromatography, what carries the pigments up the paper?
IntermediateA pigment spot moves 3.6 cm while the solvent front moves 6.0 cm. What is its Rf value?
ChallengeShould the edge of the filter paper sit above or below the rim of the funnel?
ChallengeWhere should the thermometer bulb be placed in a distillation set-up?
Challenge250 g of salt solution contains five percent salt. How much salt remains after evaporation?
Error redoA student says filtration separates the salt from salt solution. Which method should be used?

03　Answers and one-line notes

#	Answer	One-line note
1	Filtration	Sand does not dissolve, so it stays on the filter paper while the water passes through as filtrate.
2	No, the salt passes through the filter paper with the water	Dissolved particles are far too small, so filtration only holds back undissolved solids.
3	A difference in boiling point	The component with the lower boiling point vaporises first and is then condensed and collected.
4	The salt, as a solid	The water vaporises away and the dissolved salt is left behind in the dish.
5	The solvent, also called the mobile phase	The solvent climbs the paper and drags the pigments with it, and how far each travels depends on adsorption.
6	0.60	Rf is the distance moved by the spot divided by the distance moved by the solvent front, so 3.6 over 6.0 gives 0.60.
7	Below the rim of the funnel	If the paper is too high, liquid creeps between paper and funnel and bypasses the filter.
8	At the side arm of the distillation flask	The temperature wanted is that of the vapour entering the condenser, not of the boiling liquid.
9	12.5 g	250 times 0.05 equals 12.5, so 12.5 g of salt is left.
10	Evaporation, or distillation	The salt is dissolved, so the water must be removed instead, using evaporation or distillation.

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.

For separation questions ask two things: whether each component dissolves in water, and whether their boiling points or adsorption differ.Tutor Registration →

Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.