Which statement reflects proper use of a laboratory balance?

Which statement reflects proper use of a laboratory balance?

• A. Do not place any solid directly on the balance pan.
• B. Always weigh liquids directly on the scale.
• C. Use proper weighing dishes (boats) when balancing a solid.
• D. Calibrate the balance after every use.

Answer: (C)

Weighing solids with a proper weighing dish is essential because it ensures you measure only the solid’s mass, not the container, and it allows you to tare the dish to zero before adding the sample. The dish protects the delicate balance pan from residues, contamination, or damage, and it makes transferring the solid easier while minimizing loss from sticking or spills. The standard approach is to place an empty weighing dish on the balance, tare to zero, then add the solid to obtain the mass of the solid itself. This approach is preferable to weighing liquids directly on the scale, which risks spills and evaporation, and to weighing solids directly on the pan without a dish, which can contaminate the pan and complicate accurate mass measurements. Calibration is not required after every use unless your lab protocol specifies it or the balance has been moved or its environment changed.

Weighing solids with a proper weighing dish is essential because it ensures you measure only the solid’s mass, not the container, and it allows you to tare the dish to zero before adding the sample. The dish protects the delicate balance pan from residues, contamination, or damage, and it makes transferring the solid easier while minimizing loss from sticking or spills. The standard approach is to place an empty weighing dish on the balance, tare to zero, then add the solid to obtain the mass of the solid itself.

This approach is preferable to weighing liquids directly on the scale, which risks spills and evaporation, and to weighing solids directly on the pan without a dish, which can contaminate the pan and complicate accurate mass measurements. Calibration is not required after every use unless your lab protocol specifies it or the balance has been moved or its environment changed.