Chapter 10.2, Problem 18PP

(a)

Interpretation Introduction

Interpretation:

The number of moles of a given mass of Zn needs to be determined.

Concept introduction:

Number of moles in the ratio of weight to its gram molecular weight of the respective element.

Answer to Problem 18PP

Number of moles of Zn is $=1\cdot 912\times {10}^1$

Explanation of Solution

Given information:

Weight of $Zn=1\cdot 25\times {10}^3\text{ g}$

Formula used:

$\text{Number of moles = }\frac{\text{Weight}}{\text{gram molecular weight}}$

Calculation:

Given weight of $Zn=1\cdot 25\times {10}^3\text{ g}$

Atomic weight of $Zn=65\cdot 37$

Substitute these in the above formula

$\text{Number of moles = }\frac{\text{Weight}}{\text{gram molecular weight}}$

$\text{moles = }\frac{1\cdot 25\times {10}^3}{65\cdot 37}=1\cdot 912\times {10}^1=19.12\text{ mol}$

Interpretation Introduction

(b)

Interpretation:

The number of moles of given mass of Fe needs to be determined.

Concept introduction:

Number of moles in the ratio of weight to gram molecular weight of respective element.

Answer to Problem 18PP

The number of moles of $\text{Fe =}17.9\text{ mol}$

Explanation of Solution

Given information Weight of ${\text{Fe = 10}}^3\text{ g}$

Formula used:

$\text{Number of moles = }\frac{\text{Weight}}{\text{gram molecular weight}}$

Calculation:

Given weight of ${\text{Fe = 10}}^3\text{ g}$

Gram molecular weight of $\text{Fe = 55}\cdot \text{847}$

Substitute in the above formula

$\text{Number of moles = }\frac{\text{Weight}}{\text{gram molecular weight}}$

$\text{Number of moles = }\frac{{10}^3\text{ g}}{55\cdot 847\text{ g/mol}}=1\cdot 7906\times {10}^1=17.9\text{ g}$