Notes on Mole Concept
Notes on Mole Concept includes three basic terms like mole, molar mass and Avogadro’s Number.
What is 1Mole?
1 mole is an amount of a substance which contains as many particles as there are in 12 g of C-12 isotopes that is 6.022X1023
6.022X1023 is known as Avogadro’s number. It is important part of mole concept.
Mole= Mass of a substance/Molar Mass
Molar Mass is the mass of 1 mole of a substance in grams.
For example: 1 mole atoms = gram atomic mass = 6.022X1023 atoms
1 mole oxygen atoms = gram atomic mass of oxygen =16 g = 6.022X1023 atoms
1 mole molecules = gram molecular mass = 6.022X1023 molecules
1 mole oxygen molecules = gram molecular mass of oxygen =32 g =
6.022X1023 oxygen molecules
1 mole ions = formula unit mass = 6.022X1023 ions
Example – 1 mole( SO4)2- ions = formula unit mass of ( SO4)2-=96g = 6.022X1023
The mass (nucleon) number, A, is the sum of the protons and the neutrons. (= 12 for Carbon)
The atomic (proton) number, Z, of an element is the number of protons in the nucleus of the atom. In the neutral atom it is equal to the number of electrons. ( 6 for Carbon)
The Relative Atomic Mass, A(r), is the mass of one atom of an element compared to a scale in which one atom of carbon-12 has a mass of 12.0000.
The Relative Molecular Mass, M(r),is the ratio of the mass of one molecule of a substance to the mass of one atom of carbon-12. It is calculated by adding the relative atomic masses of all the atoms of all elements in the molecule.
Relative molecular mass, M(r), or relative formula mass (for those compounds that do not exist as molecules) is calculated by adding together the Relative Atomic MassA(r) ‘s of the elements in the molecular formula.