Răspuns: 32,93% Na; 22,53%S; 45,07%O
Explicație pas cu pas: [tex]M_{Na_{2}SO_{4}}=2A_{Na}+A_{S}+4A_{O}=2\cdot23+32+4\cdot16=142~\frac{g}{mol}[/tex]
[tex]142g~Na_{2}SO_{4}...23\cdot2g~Na...32g~S...4\cdot16g~O\\\\100g~Na_{2}SO_{4}...~~~~x\%Na...~y\%S~...~~~~z\%O~~\\[/tex]
[tex]x=\frac{100g\cdot2\cdot23g}{142g} $\approx$ 32,93\%Na\\\\\\[/tex]
[tex]y=\frac{100g\cdot32g}{142g} $\approx$ 22,53\%S[/tex]
[tex]z=\frac{100g\cdot4\cdot16g}{142g} $\approx$ 45,07\%O\\\\\\[/tex]
