Skip to content
InkFlaskCambridge IGCSE

Measure mass · Biology · Chemistry · Physics

Top-pan balance

Top-pan balance, with labels: pan, display, to 0.1 g, zero (tare) button.

What it is for

A top-pan balance measures mass. Put the object on the pan and the display shows its mass in grams; the tare (zero) button sets the display to 0 with a container on the pan, so only what you add is weighed.

Range
up to 500 g (the Practical Test balance)
Resolution
0.1 g (some balances show 0.01 g)
Record to
every figure shown, e.g. 24.3 g

Why choose it

For the mass of a solid, a liquid in a container, or a sample before and after heating or soaking, as with potato cylinders in osmosis. A 0.01 g balance shows smaller changes, which matters when the change is only a fraction of a gram.

How to read it

24.3 gONZEROzero with the empty beaker on the pan,then add: 24.3 g
  1. Stand the balance on a firm, level bench, away from draughts.
  2. Put the empty container on the pan and press tare, so it reads 0.0 g.
  3. Add the substance and wait until the reading stops changing.
  4. Write down every figure on the display, with the unit: 24.3 g.

Exam-style question

A student heats blue copper(II) sulfate crystals in an evaporating basin until they turn white. The empty basin has a mass of 24.3 g, the basin and crystals 29.3 g, and the basin and white solid after heating 27.5 g.

  1. Calculate the mass of crystals used.
  2. Calculate the percentage by mass of water in the crystals.
  3. How can the student be sure all the water has gone?
Show what a good answer says
  1. 29.3 − 24.3 = 5.0 g.
  2. Water lost = 29.3 − 27.5 = 1.8 g; 1.8 ÷ 5.0 × 100 = 36%.
  3. Heat, cool and weigh again until two readings in a row are the same (heating to constant mass).

Teaching points for checking your own answer, not official Cambridge marks.

Common errors

  • Forgetting to tare, so the reading includes the container.
  • Reading while the number is still changing, or with the balance in a draught or on a sloping bench.
  • Weighing something while it is still hot: rising warm air makes the reading unsteady and wrong.
  • Rounding the display (24 g) or leaving out the unit: write every figure shown, 24.3 g.

Where you use it here

From the Practical Test apparatus lists of the Cambridge IGCSE Biology 0610, Chemistry 0620 and Physics 0625 syllabuses for 2026–2028, and the apparatus the experiments on this site use.

More in “Measuring instruments”