Topic 1 of 6
Choose a measurement that answers the question
Apparatus choice depends on range, precision and what changes.
SEC G2 Science K223 / K225 (2027)
Choose a measurement that answers the question
Apparatus choice depends on range, precision and what changes.
| Quantity or task | Apparatus | Reason |
|---|---|---|
| Time | Stopwatch | Measure an interval; define exactly when timing starts and ends. |
| Temperature | Thermometer or temperature probe | Measure the reaction mixture, not the hot container wall. |
| Mass | Balance | Measure mass directly; subtract the container mass. |
| Approximate liquid volume | Measuring cylinder | Quick measurement where modest precision is sufficient. |
| One accurate fixed volume | Volumetric pipette and filler | Delivers its calibrated volume, such as 25.0 cm3. |
| Accurate variable volume | Burette | Volume delivered = final minus initial reading. |
| Gas volume | Gas syringe | Collect 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.
Check your understandingA burette reads 1.20 cm3 initially and 23.65 cm3 finally. What volume was delivered?Think it through, then reveal the answer
23.65 - 1.20 = 22.45 cm3. The final reading is not itself the delivered volume unless the initial reading was zero.