Weighing processes play a crucial role in product quality, operational efficiency and regulatory compliance. A good weighing process includes selecting appropriate equipment, setting standard operating procedures and ensuring proper calibration and maintenance.

A typical weighing system consists of load cells that support a weigh vessel or platform, a junction box, and a weight controller. The signals from the load cells are summed in the junction box and sent to the weight controller to generate a weight reading.

Mass

During the weighing process, mass is measured by using a balance. An object’s mass refers to its inertial and gravitational properties. Inertial mass measures how much resistance an object offers to a change in its motion, meaning that an object with greater mass will have a smaller change in speed or position when subjected to the same force applied to it.

Gravitational mass, on the other hand, measures an object’s effect on the Earth’s gravity. It is equal to the net force on an object divided by its acceleration. This means that your weight on the moon is different from your weight on Earth because the force of gravity is less.

Before weighing, make sure the balance is clean and free of debris. Use containers that can withstand the chemicals in your sample, and make sure the container you’re using is close to the capacity of the weighing pan. Tare the balance by briefly pressing the control bar, and wait for a row of zeros to appear.

Weight

Weighing instrument accuracy depends on following a standard operating procedure (SOP) and doing it consistently. Good weighing practice also means observing proper precautions to prevent contamination of the balance or the samples and reagents that are weighed.

For example, if you’re weighing powders that tend to stick to the weighing paper after you’ve recorded their weight, put your weighing paper in a drawer beneath the top loading balance instead of on it. This allows you to reuse it for subsequent weighings without contamination.

Another way to eliminate weighing errors is by “weighing by difference,” as illustrated in this three-minute video by Shimadzu. A beaker of a known volume is placed on the balance pan, and then the empty weighing bottle is tared with the tare button. The weight of the beaker minus the weight of the weighing bottle is then displayed on the screen. This can be repeated as many times as necessary until the correct weight is obtained.

Volume

Whether you’re measuring ingredients to bake a cake or adding potting soil to your garden, you know the importance of accurate volume measurement. Volume is the measure of three-dimensional space that a shape occupies, and it can be calculated using specific formulas.

Volume measurements are often used to compare different types of substances, and they are a crucial step in analyzing chemistry. To obtain the most precise results, you should use the correct type of receiver for the material to be weighed.

For example, fine powders may require a forceps or pipet to be transferred into a volumetric flask. You should also make sure that the weighing container and the receiver are clean and free of static charge, which could interfere with your results. Antistatic devices can be used to minimize this problem. Alternatively, you can use the double-weighing in air method to determine both volume and density. The results from this technique are comparable to those from the hydrostatic method.

Density

Density is the measure of a solid or liquid’s mass per unit volume. It is calculated as the mass divided by the volume and is expressed as a ratio in units of mass per unit volume, such as kilograms per cubic metre (kg/m3) or grams per cubic centimeter (g/cm3).

Different materials have different densities. The more dense a material is, the heavier it feels for its size. Iron and platinum are examples of dense materials, while air and feathers are less dense.

To measure density, a sample is immersed in a reference liquid and then weighed. The sample must be free of any contact with the container walls to ensure accurate measurements. For this reason, density measurements require a balance with a large capacity, especially for high-precision applications.

A hydrostatic balance is the preferred method for measuring density. This technology eliminates both short-term drifts and temperature changes, which would otherwise affect the measurement result. The calibration fluid is normally water, but the density kit can be used with a wide range of reference liquids.