Question

Which has more number of atoms? 100g of N2 or 100g of NH3 [email protected]

Answer 1

No. of moles of atoms = weight / atomic weight.

100 gms of N₂ = 100/2 x 14 moles = 100/28 moles

Number of molecules = 100 / 28 x 6.022 x 10²³

Molar mass of N₂ = 2 x molar mass of monoatomic  N

Molar mass of N₂ = 2 x 14.0067 = 28 moles.

Number of molecules = 100/28 x 6.022 x 10²³

No. of atoms = 2 x 100/28 x 6.022 x 10²³ = 43.01 x 10²³

For NH₃ :-

100 gm of NH₃ = 100/17 moles

Number of molecules = 100/17 x 6.022 x 10²³ molecules

No. of atoms in NH₃ = (1 + 3) = 4 x 100/17 x 6.022 x 10²³ = 141.69 x 10²³ atoms.

 

Therefore, NH₃ has more atoms than N₂.

Answer 2

Given :
Weight of N₂= 100g
weight of NH₃ = 100g

Molecular mass of N2=28u
Molar mass of N2=28g

Molecular mass of NH3 = [14+3x1] =17u

molar mass of NH3=17g

Calculating number of atoms  In 100g of  N2:

1mole of  N2[28 g] Contains -------------> 6.022 x 10²³ moelcules

100g contains                       ---------------->?

Number of N2 molecules = 6.022 x 10²³x100/28=21.5 moleules 
Number of N2 atoms =2x21.5=43.0 x 10 ²³

Therefore 100 g of N2 Contains 43x10²³ atoms

Calculating Number of atoms in NH3:

1mole of  NH3[17 g] Contains -------------> 6.022 x 10²³ molecules

100g contains                       ---------------->?
  Number of molecules of NH3 = 6.022x10²³ x100/17
=35.4 x 10²³ mloecules 

As NH3 contains 4 atoms = 4x 35.4 =141.6 x 10²³ atoms
∴ 100g of NH3 contains =141.6 x 10²³ atoms

Conclusion:
∴100g of NH3 has more atoms than 100g of N2 .