2NaCl + H2SO4 => Na2SO4 + 2HCl
2 moli NaCl..................1 mol H2SO4
x moli NaCl..................3 moli H2SO4
x=2*3=6 moli NaCl (nr de moli pur)
puritatea = nr moli pur/nr de moli impur*100 => nr de moli impur=nr moli pur*100/puritate = 6*100/95=6,315 moli NaCl
MNaCl=ANa+ACl=23+35,5=58,5g/mol
m=6,315*58,5=369,473g NaCl (masa impura)