Mole (unit) containing of hydrogen atoms in it, weighing exactly 1.008 grams (same as the Ar of one hydrogen atom). The molar mass of a substance is the mass of a sample divided by the amount of substance in that sample. This is a constant for any given substance. Since the unified atomic mass unit (symbol: u, or Da) is defined as 1/12 of the mass of the C atom, it follows that the molar mass of a substance, measured in grams per mole, is numerically equal to its mean atomic or molecular mass expressed in Da. One can determine the amount
Entropy entropy, have dimensions of energy divided by temperature, which has a unit of joules per kelvin (J K) in the International System of Units (or kg m s K in terms of base units). The entropy of a substance is usually given as an intensive property—either entropy per unit mass (SI unit: J K kg) or entropy per unit amount of substance (SI unit: J K mol). The French mathematician Lazare Carnot proposed in his 1803 paper "Fundamental Principles of Equilibrium and Movement" that in any machine the accelerations and shocks of the moving parts represent losses of "moment of