Question

Calculate the number of atoms in 58.7 g of NH₄NO₂. Ans: 4.42 x 10²⁴ atoms

Answer 1

First of all, we have to calculate the moles of NH4NO2.

Given, mass of NH₄NO₂ = 58.7 g

Molar Mass of NH₄NO₂ = [ 14 + 4(1) + 14 + 2(16)] = 14 + 4 + 14 + 32 = 64 g/mol

Note: Molar Mass of N = 14 g/mol, Molar Mass of H = 1 g/mol, Molar Mass of O =16 g/mol

Moles of NH₄NO₂ = mass of NH4NO2/Molar Mass of NH4NO2

= (58.7 g)/(64 g/mol) = 0.9172 mol

Number of molecules (N) = Number of moles (n) x Avogadros number (N_A)

Number of molecules of NH₄NO₂ = 0.9172 mol x 6.022 x 10²³ molecules/mol

= 5.5233 x 10²³ molecules

one molecule of NH₄NO₂ contains atoms = 8

5.5233 x 10²³ molecules of NH₄NO₂ contains atoms = 5.5233 x 10²³ x 8 = 4.419 x 10²⁴ ~ 4.42 x 10²⁴ ​atoms