Use of Laboratory Balances

This demonstration explains the correct use of analytical and top-loading balances in the laboratory. It covers accuracy requirements, weighing techniques, and best practices to ensure precise and reliable mass measurements.

1. Determine the level of accuracy needed and select the appropriate balance (analytical for high precision, top-loading for general use).
2. Check that the balance is clean, dry, and at room temperature.
3. Turn on the balance and press the tare button to reset it to zero.
4. Place your container (such as a beaker, flask, or weighing bottle) on the balance and record its mass.
5. Add your sample either by:
   1. Using the weighing by difference method (weigh container, remove a portion, reweigh, and calculate mass transferred).
   2. Using direct transfer into a tared container, ensuring no spillage or contamination.
6. For analytical balances, always close the balance doors before taking a measurement.
7. Record the mass to the proper number of significant figures according to the balance used.
8. Clean up any spills immediately and return the balance to zero before leaving.

Lab Balance Tutorial - frank deering:

📄 Proper Use of Balances - Oliver Seely: https://chem.libretexts.org/Ancillary_Materials/Demos_Techniques_and_Experiments/General_Lab_Techniques/Proper_Use_of_Balances

• Use weighing paper for top-loading balances (never for analytical balances).
• Seal and dry crucibles or samples in an oven before weighing to constant mass.
• Transfer solids using a spatula or pouring techniques, depending on the sample container.

• Do not place chemicals directly on the balance pan.
• Always use dry, clean containers to prevent mass errors and damage.
• Avoid touching samples or containers with bare hands to prevent contamination.
• Handle glassware carefully to avoid breakage.
• Clean spills inside the balance enclosure immediately.

• Why must balance doors be closed during weighing? (To prevent air currents from affecting the reading.)
• Why should warm objects not be weighed immediately? (They create convection currents and density differences that cause errors.)
• When should an analytical balance be used instead of a top-loading balance? (When four or more significant figures are required, such as for unknowns or primary standards.)
• What is the advantage of weighing by difference? (It minimizes exposure to air and provides precise measurements of transferred material.)