Chapter 10, Problem 134A

Interpretation Introduction

(a)

Interpretation:

The mass of $\text{4}\text{.50}\times {\text{10}}^{-2}{\text{ mole CuCl}}_2$ should be calculated.

Concept introduction:

Number of moles of a compound is defined as the ratio of given mass of the compound to the molar or molecular mass of the compound.

The mathematical expression is given by:

Number of moles = $\frac{\text{mass of the compound}}{\text{molar mass of the compound}}$

The one mole of any substance is equal to the Avogadro number, i.e., $6.022\times {10}^{23}$ atoms.

Answer to Problem 134A

Mass of the ${\text{CuCl}}_{\text{2}}$ = $605.25\times {10}^{-2}\text{ g}$

Explanation of Solution

Molar mass of ${\text{CuCl}}_{\text{2}}$ = $63.55\text{ g/mole +2}\left(35.45\text{ g/mole}\right)$

= 134.5 g/mole

Number of moles of ${\text{CuCl}}_{\text{2}}$ = $\text{4}\text{.50}\times {\text{10}}^{-2}\text{ mole}$

Number of moles = $\frac{\text{mass of the compound}}{\text{molar mass of the compound}}$

Put the values,

$\text{4}\text{.50}\times {\text{10}}^{-2}\text{ mole}$ = $\frac{\text{mass of the compound}}{134.5\text{ g/mole}}$

Mass of the ${\text{CuCl}}_{\text{2}}$ = $\text{4}\text{.50}\times {\text{10}}^{-2}\text{ mole}\times \text{134}\text{.5 g/mole}$

= $605.25\times {10}^{-2}\text{ g}$

Interpretation Introduction

(b)

Interpretation:

The mass of $\text{1}\text{.25}\times {\text{10}}^2{\text{ mole Ca(OH)}}_{\text{2}}$ should be calculated.

Concept introduction:

Number of moles of a compound is defined as the ratio of given mass of the compound to the molar or molecular mass of the compound.

The mathematical expression is given by:

Number of moles = $\frac{\text{mass of the compound}}{\text{molar mass of the compound}}$

The one mole of any substance is equal to the Avogadro number, i.e., $6.022\times {10}^{23}$ atoms.

Answer to Problem 134A

Mass of the ${\text{Ca(OH)}}_{\text{2}}$ = $9.26\times {10}^3\text{ g}$

Explanation of Solution

Molar mass of ${\text{Ca(OH)}}_{\text{2}}$ = $40.08\text{ g/mole +2}\left(15.999\text{ g/mole}\right)+2\left(1.0078\text{ g/mole}\right)$

= 74.093 g/mole

Number of moles of ${\text{Ca(OH)}}_{\text{2}}$ = $\text{1}\text{.25}\times {\text{10}}^2\text{ mole}$

Number of moles = $\frac{\text{mass of the compound}}{\text{molar mass of the compound}}$

Put the values,

$\text{1}\text{.25}\times {\text{10}}^2\text{ mole}$ = $\frac{\text{mass of the compound}}{74.093\text{ g/mole}}$

Mass of the ${\text{Ca(OH)}}_{\text{2}}$ = $\text{1}\text{.25}\times {\text{10}}^2\text{ mole}\times \text{74}\text{.093 g/mole}$

= $9.26\times {10}^3\text{ g}$