Question

A hydride of nitrogen contains its three halves volume of hydrogen and its vapour density is 8.5 . Determine the molecular formula of hydride of nitrogen

Answer 1

Step-by-step explanation:

Solution

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Correct option is B)

Correct option: B

Explanation:

Let, Total amount of compound be 100g

So, in 100gm sample we have 12.5g of H

So, amount of N present is 100−12.5=87.5g

The atomic mass of H is 1

mol

g

and N is 14

mol

g

.

Number of moles of compound given by formula;

Number of moles =

Molar mass

Amount of Sample

The number of moles of H =

1.5gm/mol

12gm

= 12.5mol

The number of moles of N =

14gm/mol

87.5gm

= 6.25mol

Mole ratio of N:H = 6.25:12.5=1:2

Thus, the empirical formula of the compound is NH

2

Empirical formula weight = NH

2

= 14+2×1=16 g

Molecular Formula = (NH

2

)∗

empirical formula weight

molecular weight

= (NH

2

)∗

16g/mol

32g/mol

= 2

Therefore the molecular formula is N

2

H

4

.