1.9 Chemical Analysis
Purity, melting and boiling behaviour, chromatography, flame tests, precipitation tests and identification of ions and gases.
How to study for CCEA GCSE Chemistry
Connect particle models to observations, balance every quantitative relationship, and prepare each prescribed practical from safe method through analysis and evaluation.
Core concepts
Concept 1
Analytical tests use defined reagents, observations and reference results to identify substances.
Exam cue: State test reagent, procedure and positive observation, then make the identification.
Concept 2
Chromatography separates mixture components and can compare them using positions or retention factors under the same conditions.
Exam cue: Measure distances from the same baseline when calculating an Rf value.
Concept 3
Reliable identification often combines more than one observation while controls and clean apparatus reduce contamination.
Exam cue: Use several compatible results before claiming an unknown is identified.
Risk pitfalls and guardrails
Giving an ion name without the reagent or observation that supports it.
Guardrail: Do not import an England board, Single Award or Double Award structure, and do not replace a particle-level explanation with a vague observation.
Letting the chromatography baseline sit below the solvent level.
Guardrail: Do not import an England board, Single Award or Double Award structure, and do not replace a particle-level explanation with a vague observation.
Assuming one spot proves a substance is pure under all possible conditions.
Guardrail: Do not import an England board, Single Award or Double Award structure, and do not replace a particle-level explanation with a vague observation.
Memory anchors
Rf value
Distance moved by solute divided by distance moved by solvent front.
Flame test
A characteristic flame colour can identify certain metal ions.
Precipitate
An insoluble solid formed when solutions react.
Hydrogen test
A lighted splint gives a squeaky pop.
Oxygen test
A glowing splint relights.
Carbon dioxide test
Limewater changes from colourless to milky.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
How does a pure substance usually melt?
What can an impurity do to a melting point?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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