NA₂SO₄XH₂O ON HEATING SUFFERS A LOSS OF WEIGHT OF 56% THEN FIND X , MOL.WT ?

Na₂SO₄.XH₂O -> Na₂SO₄ + X H₂O (BECOMES ANHYDROUS)

1MOLE              ==      1      == X MOLES            (== MEANS REACT)

THUS,

100/(142+18 X) == 1  == 100 X/(142+18 X)MOLES

AND WE HAVE 56/18 MOLES OF H₂O (AS 56% LOST GOES IN H₂0).

EQUATING THEM YOU GET X = 10 MOLES .....

AND THUS CALCULTE MOL WT. YOURSELF.

on heaing it looses all water molecules

let n water molecules be present in the compound before heating

its mol. wt. is : 18n + 142

loss in mol wt after heating : 18n

18n/(142+18n) = 54/100

on solving fo rn gives : n=10

the compound is NA₂SO₄.10H₂O

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regards

Ramesh