1) Na2SO3 = 2Na(+) + SO3 (2-)
=> 1 mol SO3 (2-) : 1 mol Na2SO3
2) Molar mass of Na2 SO3
223 g/mol + 32g/mol + 316 g/mol = 126 g/mol
3) moles of Na2SO3
n = grams / molar mass = 99.6mg [1 g /1000 mg] / 126 g / mol = 7.910^-4 mol Na2SOs
4) moles of ions
1 mol SO3 (2-) : 1 mol Na2SO3 => 7.910^-4 mol Na2SO3 = 7.910^-4 mol SO3 (2-)
5) number of ions
number of ions = number of ions Avogadro number
number of ions = 7.90 10^-4 mol 6.022 10^23 ions / mol = 0.0048 10^23 ions = 4.8 10^ 20 ions
Answer: 4.8 * 10^20 ions
