Search results
Results from the WOW.Com Content Network
The constants listed here are known values of physical constants expressed in SI units; that is, physical quantities that are generally believed to be universal in nature and thus are independent of the unit system in which they are measured.
s −1 ⋅kg −1 Specific activity (symbol a ) is the activity per unit mass of a radionuclide and is a physical property of that radionuclide. [ 1 ] [ 2 ] It is usually given in units of becquerel per kilogram (Bq/kg), but another commonly used unit of specific activity is the curie per gram (Ci/g).
It was originally defined as "the quantity or mass of radium emanation in equilibrium with one gram of radium (element)", [1] but is currently defined as 1 Ci = 3.7 × 10 10 decays per second [4] after more accurate measurements of the activity of 226 Ra (which has a specific activity of 3.66 × 10 10 Bq/g [5]).
In the metric system, the mass per unit area of all types of paper and paperboard is expressed in terms of grams per square metre (g/m 2).This quantity is commonly called grammage in both English and French, [2] though printers in most English-speaking countries still refer to the "weight" of paper.
The molar mass constant, usually denoted by M u, is a physical constant defined as one twelfth of the molar mass of carbon-12: M u = M(12 C)/12. [1] The molar mass of an element or compound is its relative atomic mass (atomic weight) or relative molecular mass (molecular weight or formula weight) multiplied by the molar mass constant.
That is, the molar mass of a chemical compound expressed in g/mol or kg/kmol is numerically equal to its average molecular mass expressed in Da. For example, the average mass of one molecule of water is about 18.0153 Da, and the mass of one mole of water is about 18.0153 g.
List of orders of magnitude for energy; Factor (joules) SI prefix Value Item 10 −34: 6.626 × 10 −34 J: Energy of a photon with a frequency of 1 hertz. [1]8 × 10 −34 J: Average kinetic energy of translational motion of a molecule at the lowest temperature reached (38 picokelvin [2] as of 2021)
Relative atomic mass is determined by the average atomic mass, or the weighted mean of the atomic masses of all the atoms of a particular chemical element found in a particular sample, which is then compared to the atomic mass of carbon-12. [10] This comparison is the quotient of the two weights, which makes the value dimensionless (having no ...