Na:S:O=2:1:4
M Na2SO4= 2x23+32+4x16=142 g/mol
142 g Na2SO4.............46gNa..............32gS.................64gO
100 g...........................X.....................Y......................Z
X=46x100/142=32,39%Na
Y=32x100/142=22,53%S
Z=64x100/142=45,07%O
