Balance
Top-pan balance types, taring, precision, and care for IGCSE Chemistry 0620 practical work, with common errors and Paper 6 marking points.
Published by IGCSEChemistry.com.my
Chemistry teaching team: K. S. Tan (15+ years teaching IGCSE Chemistry) and Ms Yash (10+ years teaching IGCSE Chemistry) and Ms Kartini (15+ years teaching IGCSE Chemistry).
Mapped to Cambridge IGCSE Chemistry 0620 (2026–2028). Last updated 2026-08-19.
Description
A top-pan balance is an electronic device that measures mass. It has a flat pan on top where the object or container is placed, and a digital display that shows the mass reading.
Key features:
| Feature | Typical specification |
|---|---|
| Precision | 0.01 g (2 decimal places) |
| Maximum capacity | 200 g to 600 g |
| Tare function | Resets display to zero |
| Units | Grams (g) |
| Power | Mains or battery |
How to use
- Place the balance on a flat, stable surface away from draughts and vibrations.
- Switch on and wait for the display to show 0.00 g.
- If the display does not read zero, press the tare/zero button.
- Place the container (beaker, watch glass, weighing boat) on the pan.
- Press tare to reset to 0.00 g.
- Add the substance until the desired mass is reached.
- Record the mass to the full precision of the balance (e.g., 2.54 g, not 2.5 g).
Weighing by difference
When you need to know the exact mass of substance transferred to a reaction:
- Weigh the container with the substance (record as m1, e.g., 15.62 g).
- Transfer the substance to the reaction vessel.
- Reweigh the container with any residue (record as m2, e.g., 12.08 g).
- Mass transferred = m1 - m2 = 15.62 - 12.08 = 3.54 g.
This method accounts for substance that sticks to the container and is more accurate than trying to add exactly the right mass.
Care and best practice
- Keep the balance clean. Spilled chemicals can corrode the pan.
- Never place hot objects on the pan. Convection currents cause the reading to drift.
- Shield from draughts. Some balances have a draught shield (transparent box around the pan) for this purpose.
- Calibrate periodically using a known standard mass, if available.
- Return the balance to zero and switch off after use.
- Never exceed the maximum capacity.
Common errors
Not taring: The mass includes the container, leading to incorrect values in calculations.
Recording to wrong precision: A balance reading 4.50 g must be recorded as 4.50, not 4.5. The trailing zero shows the precision of the instrument.
Draughts or vibrations: Air movement causes fluctuating readings. Wait for the reading to stabilise.
Hot objects: A hot beaker creates convection currents that make the balance read too low. Allow objects to cool to room temperature before weighing.
Chemical spills on the pan: Clean immediately to prevent corrosion. Acidic or alkaline spills can damage the pan.
Studying this yourself? Tutoring arrangements are normally made by a parent or guardian. Message us for the details to share with them, or send them this page.