JEE MAIN - Chemistry (2002 - No. 53)
In a compound C, H and N atoms are present in 9 : 1 : 3.5 by weight . Molecular weight of the compound is 108 g mol-1 . Molecular formula of compound is
C2H6N2
C3H4N
C6H8N2
C9H12N3
Explanation
Element | Weight ratio | No of atoms of element | Simplest Ratio |
---|---|---|---|
C | 9 | 9/12 = 3/4 | 3 |
H | 1 | 1/1 = 1 | 4 |
N | 3.5 | 3.5/14 = 1/4 | 1 |
Empherical Formula of the compound (EF) will be C3H4N
Now to find molecular formula at first find number of moles of given mass
No. of moles (n) =
Given mass
Molar mass
$$ \Rightarrow $$ $${{108} \over {54}}$$
$$ \Rightarrow $$ 2
$$\therefore$$ No. of Moles is 2
Molecular formula (MF) = n (no. of moles) $$\times$$ Empherical Formula (EF)
$$ \Rightarrow $$ 2 $$\times$$ C3H4N
$$ \Rightarrow $$ C6H8N2
$$\therefore$$ Option (C) is correct
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