O-Level Chemistry Separation & Gas Collection Guide (Paper 3)

TL;DR
Paper 3 regularly samples three adjacent skill sets: mixture separation (chromatography, filtration, distillation), salt preparation, and gas collection. The 2026 SEAB syllabus names all three and clarifies that gas drying steps are off the table.
Planning marks come from articulating solvent selection, heating controls, cooling/crystallisation timing, and safe gas delivery routes.
MMO, PDO, and ACE credit hinge on clean apparatus setup, precise mass/volume readings, and evaluation notes that link back to the official apparatus and reagent expectations.

Loop Back to the Chemistry Hub

Use our O-Level Chemistry Experiments hub to keep this drill aligned with the rest of your Paper 3 practice set.

1 | Syllabus cues you must reference

• SEAB’s practical techniques list highlights three related experiment families: separation (paper chromatography, filtration, distillation), salt preparation, and gas collection, with an explicit note that drying gases will not be required (SEAB 2026 syllabus, p. 27).
• Assessment objective summaries remind candidates to set up apparatus correctly, record accurate observations, and analyse data while proposing realistic improvements - the backbone of MMO, PDO, and ACE scoring (