Question
Sun May 22, 2011 By:

280 ml of sulphur vapour at ntp weigh 3.2 g. the molecular formula of the sulpher vapour is????

Expert Reply
Wed May 25, 2011
As we know density of a gas = Mass/Volume = 3.2gm / 280mL
 
Molecular mass = Molar volume x density
 
As molar volume at N.T.P = 22.4L = 22.4 x 1000mL
 
So molecular mass = 22.4 x 1000 x 3.2 / 280 = 256
 
Now molecular formula = n x Empirical formula
 
n = Molecular mass / Empirical formula mass
Empirical formula mass for sulphur is = 32
 
So, n = 256 / 32 = 8
 
Hence molecular formulaof sulphur vapour is = 8 x (S)
                                                                = S8
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