Students often ask, “What is mass?” It’s important to understand that everything around us has mass—even the air we breathe.
A basic understanding of the metric system makes converting between measurements easy. This enables communication between professionals and scientists from different countries. It also makes learning more fun. All metric measurements are based on multiples of ten, making conversions quick and intuitive.
Definition
While the terms “weight” and “mass” are often used interchangeably, they are actually distinct physical properties. The word “weight” refers to the force of gravity acting on an object, while the term “mass” describes the amount of matter contained within an object.
Unlike weight, which depends on the gravitational pull of Earth, mass is constant regardless of the location or shape of an object. Your body’s mass remains the same whether you are curled up on a sofa or stretching out on the beach.
Measuring mass is essential to a number of technological applications, from weighing scales to industrial processes. Accurate mass measurements allow for quality control in manufacturing and ensure consistency in products. In scientific research, mass measurements enable researchers to study the atomic and molecular makeup of objects. For example, mass spectrometry allows scientists to analyze complex mixtures of compounds using high-sensitivity instruments. The resulting data can help improve the efficiency of agricultural production by enabling the optimization of fertilizer application.
Units
The most basic unit for measuring mass is the gram (g), which can also be expressed as kilograms (kg) in the metric system. In the United States, pounds (lb) can also be used to measure mass.
Students should be aware that the term mass is different from weight. The latter is a property of matter that depends on the gravitational field, but the former is a fundamental quantity. Students should also be aware that the verb “to weigh” is inappropriate for describing how an object’s mass is measured.
Each of the seven base units of the metric system has a corresponding name, symbol and meaning. These units can be turned into larger or smaller measurements by adding or subtracting a prefix, as shown in Table 2. For example, kilo (k) is equal to 1000 (the meaning of the number) grams. Similarly, litre (L) is equal to 1 cubic meter (1 dm3). These measurements are all very important in chemistry, and students should learn how to convert between these units as needed.
Applications
Many industrial applications rely on mass measurements. In manufacturing, for example, accurate mass measurement is critical to quality control and consistency. It is also an important aspect of analytical chemistry, allowing researchers to identify unknown compounds via their molecular weight determinations and quantify known ones.
The concept of mass is a fundamental one in physics and is one of the seven SI base units. Measurements of mass can be made using a balance or other instruments, such as graduated cylinders and density bottles. A comparison of an unknown sample with a known reference provides an estimation of its mass, and the estimation can be corrected by referencing to a standard calibration compound (see Waters Micromass oa-TOF Instruments for more).
Exact mass measurement has received increased attention recently with the development of smaller and more affordable magnetic sector instruments such as our oa-TOF line. These are particularly valuable for measuring the change in mass following deposition, etch and clean processes.
Future developments
The recent CDF measurement of the W boson mass shows that high-precision measurements will play a crucial role in future experiments. Whether the search for new physics is successful or not, it is clear that precision will be important.
It is therefore essential to statistically treat accurate mass measurements and to use terminology that describes these procedures consistently. This paper is designed to clarify and recommend appropriate terms for these purposes.
A new method of measuring the density of a mass standard was developed at NIST by immersing the standard in a bath of fluorocarbon fluid and then comparing it to volume standards. This new technique achieves a combined standard uncertainty of less than 0.01 %.
NIST is also leading efforts to redefine the kilogram, which currently consists of a lump of metal kept in France. This will make the international standard for mass a property of nature rather than a physical object. This could help to further improve the stability of mass standards and transfer standards.