A Dalton (Da) is a unit of mass used in the field of chemistry and molecular biology to express the molecular weight or mass of atoms, molecules, and compounds. It is named after John Dalton, a British chemist and physicist who contributed to the development of modern atomic theory.
One Dalton (Da) is defined as one twelfth of the mass of an unbound carbon-12 atom, which is roughly equivalent to 1.66053906660 x 10^-27 kilograms. This definition was adopted as the standard for atomic mass units (u) and is now used internationally.
Daltons are useful in the following contexts:
Atomic and Molecular Mass: The molecular weight or mass of a molecule is often expressed in Daltons. For example, the molecular weight of water (H2O) is approximately 18.01528 Da, which means that one molecule of water has a mass of approximately 18.01528 Daltons.
Proteomics and Biochemistry: In biology, particularly in the study of proteins, the mass of biomolecules like proteins and nucleic acids is often measured in Daltons. This is important for understanding their structure and function.
Mass Spectrometry: Mass spectrometry is a powerful analytical technique used to determine the mass and composition of molecules. Mass spectrometry results are often reported in Daltons.
Chemical Reactions: In chemical reactions, the mass of reactants and products can be expressed in Daltons to understand the stoichiometry of the reaction.
In the United States, a "hundredweight" (abbreviated as cwt) is a unit of weight or mass used in various industries, especially in agriculture and commerce. The hundredweight is equivalent to 100 pounds (lbs). It is often used to express weights or quantities of goods, particularly in contexts like the sale of agricultural products, grains, and some industrial materials.
1 hundredweight (US) = 100 pounds (lbs)
Hundredweights are commonly used in trade and commerce, especially for bulk items where the use of pounds or tons may not be as convenient. It provides a middle-ground unit for measuring weight between the pound and the ton. When you see prices or quantities listed in hundredweights in the United States, it means that they are referring to units of 100 pounds each.