Question

Calculate number of atoms in: (Atomic masses: N=14u, H=1u)
(i) 100 g of nitrogen gas

Answer 1

Answer:

2.15 x $10^{24}$

Explanation:

Mass of Nitrogen gas($N_{2}$) = 100g

Molar mass of Nitrogen gas($N_{2}$) = 2 x 14 = 28g/mol

No. of moles in $N_{2}$ gas = 100/28 = 3.57 moles

No. of atoms = 3.57 x $N_{A}$ where $N_{A}$ is  Avogadro number

                      = 3.57 x 6.022 x $10^{23}$

                      = 21.5 x $10^{23}$

                      = 2.15 x $10^{24}$