Question

How many molecules of P₄ are present in 8 grams of phosphorus?

Answer 1

Molar mass of P₄ molecule = 124 g/mol

Given mass of phosphorus = 8 gm

Therefore, number of moles of P₄ in 8 grams = 8/124 = 0.0645

Number of molecules in 1 mole of P₄ = 6.022 x 10²³

Number of molecules in 0.0645 mole of P₄ = 6.022 x 10²³ x 0.0645

= 0.3884 x 10²³

= 3.88 x 10²²

Hence, number of molecules of P4 in 8 gm phosphorus = 3.88 x 10²²