Mole and Molar Mass

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Summary

1. A mole of any substance contains 6 X 1023 particles.

2. 6 X 1023 is called the Avogadro’s constant or Avogadro’s number.

3. Molar mass refers to the mass of one mole of a substance. It has the same value as Ar or Mr

.

Molar Mass

2.Mass of one mole of atoms of the element particles e.g atoms, molecules or ions

6 x 1023 atoms = 1 mole of atoms = _____ g /mol

MOLAR MASS

Formulae to remember

1.(a) Number of moles = Number of particles 6 x 1023 (Avogadro’s constant)

OR

(b) Number of moles x 6 x 1023 = Number of particles

Formulae to Remember

2. (a) Relationship between mole and molar mass

Number of moles of an element

= mass of element in grams relative atomic mass of the element

Moles = Mass Ar

Formulae to Remember

2 (b) Mass of one mole of substances (covalent compounds)

= mass of substance in grams relative molecular mass

(c) Mass of one mole of substance (ionic compounds)

= mass of substances in grams relative formula mass

Moles = Mass Mr