Question

Calculate number of atoms present in:

(i) 0.1 mole of sulphur.

(ii) 2 moles of phosphors.

Answer 1

(i) 1 mole = 6.022 × 10²³

0.1 mole = 0.1 × 6.022 × 10²³ = 6.022 × 10²² molecules

1 mole of sulphur (S₈) contains = 8 atoms

Hence, no of atoms present = 8 × no. of molecules

⇒ Number of atoms present = 8 × 6.022 × 10²² molecules

⇒ Number of atoms present = 4.8 × 10²³ atoms

Thus, number of atoms present in 0.1 mole of sulphur is 4.8 × 10²³ atoms.

(ii) 1 mole = 6.022 × 10²³

2 mole = 2 × 6.022 × 10²³ molecules

1 mole of phosphorus (P₄) contains = 4 atoms

Hence, no of atoms present = 4 × no. of molecules

⇒ Number of atoms present = 4 × 2× 6.022 × 10²³ molecules

⇒ Number of atoms present = 4.8 × 10²⁴ atoms

Thus, number of atoms present in 2 mole of phosphorus is 4.8 × 10²⁴ atoms.