Chapter 10, Problem 128A

Interpretation Introduction

(a)

Interpretation:

The number of moles of oxygen atoms in 2.50 mol of KMnO₄ needs to be determined.

Concept introduction:

The number of moles of any atom in 1 mol of the compound can be determined from its molecular formula. The subscript of atom in the formula gives the number of moles of atom present in the compound.

Answer to Problem 128A

10 mol of O atoms.

Explanation of Solution

The given formula of compound is KMnO₄.

From the above formula, the number of moles of O in 1 mol of KMnO₄ is 4 mol. Thus, number of moles of O atom in 2.5 mol of KMnO₄ will be:

$n_O=4\times 2.5=10\text{ mol}$

Thus, the number of moles of O atom is 10 mol.

Interpretation Introduction

(b)

Interpretation:

The number of moles of oxygen atom in 45.9 mol of CO₂ needs to be determined.

Concept introduction:

The number of moles of any atom in 1 mol of the compound can be determined from its molecular formula. The subscript of atom in the formula gives the number of moles of atom present in the compound.

Answer to Problem 128A

91.8 mol.

Explanation of Solution

The given formula of compound is CO₂.

From the above formula, the number of moles of O in 1 mol of CO₂ is 2 mol. Thus, number of moles of O atom in 45.9 mol of CO₂ will be:

$n_O=2\times 45.9=91.8\text{ mol}$

Thus, the number of moles of O atom is 91.8 mol.

Interpretation Introduction

(c)

Interpretation:

The number of moles of oxygen atom in $1.25\times {10}^{-2}{\text{ mol of CuSO}}_{\text{4}}·{\text{5H}}_{\text{2}}\text{O}$ needs to be determined.

Concept introduction:

The number of moles of any atom in 1 mol of the compound can be determined from its molecular formula. The subscript of atom in the formula gives the number of moles of atom present in the compound.

Answer to Problem 128A

$0.1125\text{ mol}$.

Explanation of Solution

The given formula of compound is ${\text{CuSO}}_{\text{4}}·{\text{5H}}_{\text{2}}\text{O}$

From the above formula, the number of moles of O in 1 mol of is 9 mol. Thus, number of moles of O atom in $1.25\times {10}^{-2}\text{ mol}$ will be:

$n_O=9\times 1.25\times {10}^{-2}=0.1125\text{ mol}$

Thus, the number of moles of O atom is $0.1125\text{ mol}$.