A COMPOUND ON ANALYSIS GAVE THE FOOLOWING % COMPOSITION
Na=14.31%  S= 9.97%  H=6.22% O=69.50%  calculate the molecular formula of the compound on the assumption that all the hydroden in the compound is present in composition with oxygen as water of crystrallization. molecular mass of compound is 322.

Asked by patidarshm | 11th Dec, 2015, 11:28: AM

Expert Answer:

Calculate empirical formula:

 

Element

Symbol

Percentage of element

At. Mass of element

Relative no. of atoms =

Percentage/At. Mass

Simplest atomic ratio

Simplest whole no. atomic ratio

Sodium

Na

14.31

23

14.31/23=0.62

0.62/0.31=2

2

Sulphur

S

9.97

32

0.31

1

1

Hydrogen

H

6.22

1

6.22

20

20

Oxygen

O

69.50

16

4.34

14

14

 

Thus, the empirical formula of the compound is = Na2SH20O14

The empirical formula mass of the compound = 2×23+1×32+20×1+14×16= 322

Now, calculate value of n = Molecular mass / Empirical mass = 322/322=1

Finally, calculate molecular formula of the compound = n × Empirical formula= 1 × Na2SH20O14

Hence, molecular formula of the compound = Na2SH20O14

Answered by Prachi Sawant | 13th Dec, 2015, 11:59: AM