puritatea = m pur/ m impur*100 => m pur= puritatea*m impur/100 = 50*117/100=58,5g Na pur.
MNa=23g/mol
MNaCl=ANa+ACl=23+35,5=58,5g/mol
2Na + 2HCl -> 2NaCl + H₂
2*23g Na...................2*58,5g NaCl
58,5 Na............................xg
x=58,5*2*58,5/46 = Calculeaza !!