Answer : The number of [tex]SO_3^{2-}[/tex] ions are, [tex]47.57\times 10^{19}[/tex]
Explanation : Given,
Mass of [tex]Na_2SO_3[/tex] = 99.6 mg = 0.0996 g
Conversion used : (1 mg = 0.001 g)
Molar mass of [tex]Na_2SO_3[/tex] = 126.05 g/mole
First we have to calculate the moles of [tex]Na_2SO_3[/tex].
[tex]\text{Moles of }Na_2SO_3=\frac{\text{Mass of }Na_2SO_3}{\text{Molar mass of }Na_2SO_3}=\frac{0.0996g}{126.05g/mole}=7.90\times 10^{-4}moles[/tex]
Now we have to calculate the number of [tex]SO_3^{2-}[/tex].
As we know that, [tex]Na_2SO_3[/tex] dissociate to give 2 moles of [tex]Na^+[/tex] and 1 mole of [tex]SO_3^{2-}[/tex].
From this we conclude that,
As, 1 mole contains [tex]6.022\times 10^{23}[/tex] number of [tex]SO_3^{2-}[/tex] ions
So, [tex]7.90\times 10^{-4}moles[/tex] mole contains [tex](7.90\times 10^{-4})\times (6.022\times 10^{23})=47.57\times 10^{19}[/tex] number of [tex]SO_3^{2-}[/tex] ions
Therefore, the number of [tex]SO_3^{2-}[/tex] ions are, [tex]47.57\times 10^{19}[/tex]
