Question

Calculate the number of molecules of nitrogen in 7g of nitrogen.

Answer 1

N2=2×14 g =28g
28 gram of Nitrogen contains 6×10^23 molecules
7 gram of Nitrogen contains 1.5×10^23 molecules.

Answer 2

Given :

mass of N₂ = 7 g

To Find :

The number of molecules of nitrogen in 7g of nitrogen.

Solution :

Molar mass of N₂ = (14×2) gm = 28 gm

We know, 1 mol of any substance contains 6.022×10²³ molecules

Thus,

28 gm of N₂ contains 6.022×10²³ molecules

1 gm of N₂ will contain  $\frac{6.022 * 10^2^3}{28}$ molecules

7 gm of N₂ will contain $\frac{6.022 * 10^2^3}{28}$×7 molecules

                                   = 1.5 × 10²³ molecules

Therefore, 1.5 × 10²³ molecules are present in 7 g of Nitrogen.