Calculate the number of atoms in each of the following (i) 52 moles o

1.	Calculate the number of atoms in each of the following (i) 52 moles of Ar (ii) 52 u of He (iii) 52 g of He.
Answer» (i) 1 mol of Ar = 6.022×10²³atoms ∴ 52 mol of Ar = 52×6.022×10²³atoms = 3.131×10²⁵atoms (ii) 1 atom of He = 4 u of He 4 u of He = 1 Atom of He ∴ 52 u of He = (1/4) × 52 = 13 atoms (iii) 1 mol of He = 4 g = 6.022×10²³atoms ∴ 52 g of He = (6.022×10²³/4) × 52 atoms = 7.8286×10²⁴atoms

Calculate the number of atoms in each of the following (i) 52 moles of Ar (ii) 52 u of He (iii) 52 g of He.

Answer»

(i) 1 mol of Ar = 6.022×10²³atoms

∴ 52 mol of Ar = 52×6.022×10²³atoms = 3.131×10²⁵atoms

(ii) 1 atom of He = 4 u of He 4 u of He = 1 Atom of He

∴ 52 u of He = (1/4) × 52 = 13 atoms

(iii) 1 mol of He = 4 g = 6.022×10²³atoms

∴ 52 g of He = (6.022×10²³/4) × 52 atoms

= 7.8286×10²⁴atoms