Question

Calculate the number of particles in each of the following.

a) 46 g of Na 

b) 8 g of O₂ 

c) 0.1 mole of hydrogen

Answer 1

a) 46 g of Na : 

Atomic weight of Na = 23 Number of particles in 23 g of Na atom = 6.022 × 10²³ 

Number of particles in 46 g of Na atom = \(\frac{46}{23}\) x 6.022 x 10²³ = 12.044 x 10²³

b) 8 g of O₂ : 

Molecular weight of O₂ is 32. 

Number of particles in 32 g of O₂ molecule = 6.022 x 10²³    

Number of particles in 8 g of O₂ molecule = \(\frac{8}{32}\) x 6.022 x 10²³ = 1.5055 x 10²³

c) 0.1 mole of hydrogen :

Atomic weight of hydrogen is 1. 

Number of particles in 1 mole of hydrogen = 6.022 × 10²³ 

Number of particles in 0.1 mole of hydrogen= \(\frac{0.1}{1}\) × 6.022 × 10²³ = 6.022 × 10²³