Question on Empirical Formula.

Asked by RACHIT_MAHAAN | 18th Jul, 2010, 05:12: PM

Expert Answer:

Divide the percentage by atomic mass of each:
Al =10.5/27 = 0.39
K =15.1/39= 0.39
S =24.96/32 = 0.78
O = 49.92/16 = 3.12

The simple ratios are = Al:K:S:O = 1 : 1 : 2 : 8

Ans: Empirical formula = KAlS2O8

Molar mass of anhydrorus salt = 258.21

This was 54.4% of the mass of the hydrated compound

Therefore the hydrated compond has a mass of 258.21/0.544 = 474.65

The mass due to water would be 474.65 - 258.21 = 216.44 

This is equal to 12 moles of water.

The compound is KAl(SO4)2.12H2O

Answered by  | 21st Jul, 2010, 01:49: PM

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