O-Level Chemistry Thermal & Calorimetry Investigations

TL;DR
Paper 3 regularly probes exothermic/endothermic reactions via temperature tracking, and the SEAB syllabus expects candidates to manipulate calorimeters, probes, and data-loggers confidently.
Planning marks rely on setting up insulated apparatus, identifying key variables, and referencing the polystyrene cup equipment on SEAB's apparatus list.
To unlock MMO/PDO/ACE marks, record temperatures at consistent intervals, extrapolate maximum temperature changes, quote uncertainties, and recommend refinements to reduce heat loss.

1 | Thermal experiments in the syllabus

• SEAB's Paper 3 techniques include “speeds of reaction that may involve measuring of quantities, e.g. temperature,” and the apparatus list explicitly features a polystyrene (or plastic) cup of ~150 cm³ for calorimetry (SEAB 2026 syllabus, pp. 27 – 28).
• Planning, MMO, PDO, and ACE descriptors require candidates to design controlled methods, take precise readings, present data effectively, and evaluate errors (SEAB 2026 syllabus, pp. 25 – 26).
• The MOE lab safety guide reiterates the need for eye protection during exothermic reactions and careful handling of hot solutions (MOE 2021 safety guide).

2 | Planning the calorimetry workflow

1. Aim & equation. Example: “Determine the temperature change when dilute hydrochloric acid reacts with sodium hydroxide.”
2. Variables. Fixed volumes (e.g., 50 cm³ each), initial temperature equilibration, insulation (polystyrene cup + lid), stirring rate, and reaction order of addition.
3. Apparatus. Polystyrene cup in a 250 cm³ beaker for stability, thermometer (–10 °C to +110 °C), measuring cylinders (50 cm³), glass rod, stopwatch, and data-logger thermometer (if provided).
4. Method.
   • Record initial temperatures of both solutions.
   • Combine reactants rapidly in the cup, stir, and record temperature every 30 s until a maximum (or minimum) is observed and the mixture begins to cool.
   • If plotting a cooling curve, continue for several minutes after the peak to allow extrapolation back to the mixing point.
5. Risk assessment. Highlight acid/alkali hazards, the need for goggles, and safe disposal of neutralised mixtures.

3 | MMO & PDO expectations

• Consistent timing.