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Mole

 A mole is defined as the amount(mass) of a substance that contains 6.022 × 10²³number of particles (atoms, molecules or formula units). It establishes a link between mass of a substance and number of particles as shown in summary of molar calculations.

•It is abbreviated as 'mol'.

Mass of a substance is either one of the following: atomic mass, molecular mass or formula mass. These masses are expressed in atomic mass units (amu). But when these masses are expressed in grams, they are called as molar masses.

 •Scientists have agreed that Avogadro's number of particles are present in one molar mass of a substance. Thus, quantitative definition of mole is the atomic mass, molecular mass or formula mass of a substance expressed in grams is called mole.

For example:

Atomic mass of carbon expressed as 12 g = 1 mol of carbon

Molecular mass of H2O expressed as 18 g = 1 mol of water

Molecular mass of H2SO4 expressed as 98 g = 1 mol of H2SO4

Formula mass of NaCl expressed as 58.5 g = 1 mol of NaCl

 •The relationship between mole and mass can be expressed as:


Or,

 Mass of substance (g) = number of moles x molar mass

Summary showing a relationship between a substance and a mole.



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