Name: Avogadro's Law and Its Uses
Uploaded: 2019-07-19
Duration: 10 min 28 s
Description: Avogadro's law is an experimental gas law relating the volume of a gas to the amount of substance of gas present. Let us learn more through this video.

Question

Nitrogen and oxygen combine to form many oxides. In some oxides, $14 g$ of nitrogen combine with either $16 g$ of oxygen or $32 g$ of oxygen. In some other oxides, $28 g$ of nitrogen combine with $16, 48$ or $80 g$ of oxygen.

i) What are formulae of the oxides?

ii) What law of chemical combination does the formation of these compounds illustrate?

Accepted Answer

In the given compounds, nitrogen and oxygen combine as follows:

Compound Weight of Nitrogen $(N)$ Weight of Oxygen $(O)$

I $14 g$ $80 g$

II $14 g$ $32 g$

III $28 g$ $16 g$

IV $28 g$ $48 g$

V $28 g$ $80 g$

Let us take a fixed mass of nitrogen, i.e., $28 g$ . The weights of oxygen combining with $28 g$ of nitrogen in these compounds will be as follows:

Compound Weight of Nitrogen $(N)$ Weight of Oxygen $(O)$

I $32 g$ $32 g$

II $28 g$ $64 g$

III $28 g$ $16 g$

IV $28 g$ $48 g$

V $28 g$ $80 g$

Since, the atomic mass of nitrogen is $14$ and that of oxygen is $16$ , the number of atoms of $N$ and $O$ in these compounds and their formulae can be obtained as follows:

Compound Weight of Nitrogen $(N)$ Weight of Oxygen $(O)$ Gram atoms of $N$ Gram atoms of $O$
Formula

(Taking simplest ratio)

I $28 g$ $32 g$ $2$ $2$ $NO$

II $28 g$ $64 g$ $2$ $4$ ${NO}_{2}$

III $28 g$ $16 g$ $2$ $1$ $N_{2} O$

IV $28 g$ $48 g$ $2$ $3$ $N_{2} O_{3}$

V $28 g$ $80 g$ $2$ $5$ $N_{2} O_{5}$

Thus, the formulae of the given oxides are $NO, {NO}_{2}, N_{2} O, N_{2} O_{3}$ and $N_{2} O_{5}$ .

The ratio of weights of oxygen combining with $28 g$ of nitrogen are $2 : 4 : 1 : 3 : 5$ . Which is a simple whole number ratio. Hence, the formation of these compounds illustrate law of multiple proportions.

Chapter-Wise 3D Chemistry Videos from Dr. H.C. Srivastava ISC Nootan Chemistry Volume 1 for Class XI

Avogadro's Law and Its Uses

Determination of Relative Molecular Masses

Chemical Equivalent

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