Question

An oxide of nitrogen has a molecular weight of 92. Find the total no.of electrons in one gram mole of that oxide

Answer 1

The atomic numbers of nitrogen and oxygen are one half their mass numbers. Hence, one molecule of compound having molecular weight of 92 will contain 46 electrons. So, 1 gram mole of molecule will contain 46N electrons. Here, N is the Avogadro number.

Explaining further,

For nitrogen,

Atomic number, Z = 7

Mass number , A = 14

Mass number / Atomic number = A/Z = 2.

For oxygen,

Z = 8

A= 16

A/Z = 2.

So an oxide of N, will only have N and O and hence the A/Z ratio of oxide will also be 2.

For oxide,

A/Z = 2

A = 92 (given)

Hence, Z = A/2 = 46.

We know,
Z is atomic number, which is number of protons. As oxides are neutral, Atomic number is same as number of electrons, = 46.

1 molecule of oxide has 46 electrons.

1 mole oxide has 1 N molecules, N= Avogadro number.

Hence 1 mole / gram mole oxide has 46 N electrons.

Hence, answer is 46N