what is the formula for the sodium sulfate if 3.54g of dry solid remain after 8.50g of hydrate are heated??

Answer 1

hydrate ==> anhydrous + H2O
..8.50g......3.54.......4.96

mols Na2SO4 = 3.54/142 = about 0.0249
mols H2O = 4.96/18 = about 0.275
0.0249/0.0249 = 1.000
0.275/0.0249 = 11.0
empirical formula is Na2SO4.11H2O based on these data.

Answer 2

thank you, very helpful