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K326 / K328 / 2027
Experimental Chemistry

Lesson 1 of 6

Choose a measurement that answers the question

Apparatus choice depends on range, precision and what changes.

O-Level 5086 / 5088 (2026) / SEC G3 K326 / K328 (2027)

  • I can select measuring apparatus.Syllabus

    Syllabus K326 / K328, 1.1(a). Select measuring apparatus

  • I can select simple experimental setups.Syllabus

    Syllabus K326 / K328, 1.1(b). Select simple experimental setups

Choose a measurement that answers the question

Apparatus choice depends on range, precision and what changes.

Match apparatus to a task
Quantity or taskApparatusReason
TimeStopwatchMeasure an interval; define exactly when timing starts and ends.
TemperatureThermometer or temperature probeMeasure the reaction mixture, not the hot container wall.
MassBalanceMeasure mass directly; subtract the container mass.
Approximate liquid volumeMeasuring cylinderQuick measurement where modest precision is sufficient.
One accurate fixed volumeVolumetric pipette and fillerDelivers its calibrated volume, such as 25.0 cm3.
Accurate variable volumeBuretteVolume delivered = final minus initial reading.
Gas volumeGas syringeCollect gas directly and read the change in volume.

Read a liquid meniscus at eye level to avoid parallax; for a clear aqueous solution read its bottom. Record units and precision consistently. A larger container is not automatically more accurate. A pipette supplies one fixed volume; a burette is appropriate when the required volume is found during a titration.

Worked exampleMeasure a rate rather than an endpoint

Compare how magnesium reacts with two acid concentrations.

Try it first. Then show the worked stepsHide the worked steps
  1. Use equal masses and surface areas of magnesium, equal acid volumes and the same initial temperature.
  2. Collect hydrogen in an airtight gas-syringe setup and record volume at regular times.
  3. Compare initial gradients or the time to reach the same selected volume; repeat to assess consistency.
Answer

Gas volume against time reveals rate. Final gas volume alone may be identical despite different rates.

Check your understanding

A burette reads 1.20 cm3 at the start and 23.65 cm3 at the end. What volume was delivered?

  1. 23.65 cm3, the reading at the end of the titration
  2. 24.85 cm3, the two burette readings added together
  3. 22.45 cm3, the final reading minus the initial reading
Show the answer

22.45 cm3, the final reading minus the initial reading

23.65 - 1.20 = 22.45 cm3. The final reading is the delivered volume only if the burette started at 0.00 cm3.