Question

how many molecules of tetraphosphorus decaoxide are present in 4.31 moles of this compound ?

and

how many moles of tetraphosphorus decaoxide are present in 1.07x10^22 molecules of this compound ?

Answer 1

We know that , 1 mole of substance contain Avogadro's number of particles.

$\therefore$ 1 mole of P₄O₁₀ will contain 6.022 $\times$ 10 ²³ P₄O₁₀ molecules.

$\therefore$ P₄O₁₀ molecules present in 4.31 mol P₄O₁₀ = 4.31 mol P₄O₁₀$\times$ (6.022 $\times$ 10 ²³ P₄O₁₀ molecules /1 mol P₄O₁₀

P₄O₁₀ molecules present in 4.31 mol P₄O₁₀ = 2.595 $\times$ 10 ²⁴ P₄O₁₀ molecules

ANSWER : 2.60 $\times$ 10 ²⁴ P₄O₁₀ molecules

PART 2

mol of P₄O₁₀ present in 1.07 $\times$ 10 ²² P₄O₁₀ molecules

= 1.07 $\times$ 10 ²² P₄O₁₀ molecules $\times$ ( 1 mol P₄O₁₀ / 6.022 $\times$ 10 ²³ P₄O₁₀ molecules )

= 1.7768 $\times$ 10 ^-03   mol P₄O₁₀

ANSWER : 1.78  $\times$ 10 ^-03   mol P₄O₁₀