Every practical question starts with the same choices: what to measure, which apparatus to use and how precise it needs to be. Learn the apparatus for time, temperature, mass and volume, and the words that describe solutions and mixtures.
Choose apparatus to match the quantity and the precision needed. Time is measured with a stopwatch or stop-clock, temperature with a thermometer, mass with a balance, and volume with a burette (variable volumes, to 0.05 cm3), a volumetric pipette (one fixed volume, very accurately), a measuring cylinder (quick but less precise) or a gas syringe (volumes of gas). A solvent dissolves a solute to make a solution; a saturated solution holds the maximum amount of solute at that temperature. After filtration, the solid left in the filter paper is the residue and the liquid that passes through is the filtrate.
Each quantity has its own apparatus. For volume, the choice depends on whether the volume is fixed or variable, liquid or gas, and how precise it must be.
| Quantity | Apparatus | Typical resolution | Unit |
|---|---|---|---|
| time | stopwatch or stop-clock | 0.01 s (but reaction time limits it) | s |
| temperature | thermometer | 0.5 or 1 °C | °C |
| mass | electronic balance | 0.01 g | g |
| volume of liquid (variable) | burette | 0.05 cm3 | cm3 |
| volume of liquid (fixed, e.g. 25.0 cm3) | volumetric pipette | very accurate single volume | cm3 |
| volume of liquid (rough) | measuring cylinder | 0.5 to 1 cm3 | cm3 |
| volume of gas | gas syringe | 1 cm3 | cm3 |
Read a liquid volume at eye level, from the bottom of the meniscus. 1 dm3 = 1000 cm3.
Four quick checks. Each correct answer earns XP and records this skill on your profile.
Which apparatus measures a fixed volume of 25.0 cm3 of solution most accurately?
Which apparatus is used to measure the volume of gas given off in a reaction?
Sand and salt water are filtered. What is the residue?
What is a saturated solution?
Questions on separation and titration use these terms precisely. Learn the definitions word for word.
Evaluating a method: say what limits accuracy (gas escaping before the bung goes on, heat lost to the air, a reaction too fast to time) and suggest a specific improvement (use a gas syringe instead of collecting over water if the gas is soluble, lag the beaker, use more dilute acid).
The filtrate is what passes through the paper, the residue is what stays behind: do not swap them. A measuring cylinder is not suitable for a titration, and a gas collected over water must be only slightly soluble (carbon dioxide and ammonia are better measured with a gas syringe). Always give a volume read from a burette to 2 decimal places, ending in 0 or 5.
Unlocks once the four checks above are done. Worth more XP, written to IGCSE Paper 2 and Paper 4 standard.
Which reading is correctly recorded from a burette?
A student measures the volume of carbon dioxide produced by collecting it over water. Why is the measured volume too low?
In the solution formed when sugar dissolves in water, which word describes the sugar?
Which change would most improve the precision of measuring 20 cm3 of acid for a rate experiment?
This skill is now recorded on your profile. Keep the chain going.