The mass of substance which consists the equal number of particles as 12 grams of Carbon-12 is said to be mole.
For example:
The balanced chemical equation for production of water from hydrogen and oxygen is:
[tex]2H_2(g) + O_2(g) \rightarrow 2H_2O(l)[/tex]
That means 2 moles of [tex]H_2[/tex] reacts with 1 mole of [tex]O_2[/tex] to give 2 moles of [tex]H_2O[/tex].
The given formula is [tex]4Na_2SO_3[/tex].
Hence, 4 represents the number of moles in [tex]4Na_2SO_3[/tex] formula that is 4 moles of [tex]Na_2SO_3[/tex].
The number of atoms of sodium, [tex]Na[/tex] in [tex]4Na_2SO_3[/tex] is:
[tex]4 \times 2 = 8[/tex]
The number of atoms of sulfur, [tex]S[/tex] in [tex]4Na_2SO_3[/tex] is:
[tex]4 \times 1 = 4[/tex]
The number of atoms of oxygen in, [tex]O[/tex] in [tex]4Na_2SO_3[/tex] is:
[tex]4 \times 3 = 12[/tex]
