Chapter 15, Problem 89A

a.

Interpretation Introduction

Interpretation: To give the color of the solution.

Concept Introduction: The compound consisting of water of hydration (water in a crystal) is called a hydrate. The hydrates are written in a manner that the number of water molecules is written after writing the compound separated by a dot.

Answer to Problem 89A

The color of the solution is pink.

Explanation of Solution

The color of cobalt chloride test paper is blue in color. The cobalt (II) chloride hexahydrate is heated it breaks the water of hydration and results in cobalt (II) chloride.

  ${\text{CoCl}}_{\text{2}}{\text{.6H}}_{\text{2}}\text{O}\stackrel{\text{Heat}}{\to }{\text{CoCl}}_{\text{2}}+{\text{6H}}_{\text{2}}\text{O}$

When cobalt (II) chloride hexahydrate which is pink in color reacts with water, it results in a pink-colored solution.

b.

Interpretation Introduction

Interpretation: To give the color of wet cobalt (II) chloride.

Concept Introduction: The compound consisting of water of hydration (water in a crystal) is called a hydrate. The hydrates are written in a manner that the number of water molecules is written after writing the compound separated by a dot.

Answer to Problem 89A

The color of wet cobalt (II) chloride is pink.

Explanation of Solution

The color of cobalt chloride test paper is blue in color. The cobalt (II) chloride hexahydrate is heated it breaks the water of hydration and results in cobalt (II) chloride.

  ${\text{CoCl}}_{\text{2}}{\text{.6H}}_{\text{2}}\text{O}\stackrel{\text{Heat}}{\to }{\text{CoCl}}_{\text{2}}+{\text{6H}}_{\text{2}}\text{O}$

When cobalt (II) chloride hexahydrate which is pink in color reacts with water, it results in a pink-colored solution.

The color of wet cobalt (II) chloride is pink in color.

c.

Interpretation Introduction

Interpretation: To give the color of dry cobalt (II) chloride.

Concept Introduction: The compound consisting of water of hydration (water in a crystal) is called a hydrate. The hydrates are written in a manner that the number of water molecules is written after writing the compound separated by a dot.

Answer to Problem 89A

The color of dry cobalt (II) chloride is blue.

Explanation of Solution

The color of cobalt chloride test paper is blue in color. The cobalt (II) chloride hexahydrate is heated it breaks the water of hydration and results in cobalt (II) chloride.

  ${\text{CoCl}}_{\text{2}}{\text{.6H}}_{\text{2}}\text{O}\stackrel{\text{Heat}}{\to }{\text{CoCl}}_{\text{2}}+{\text{6H}}_{\text{2}}\text{O}$

When cobalt (II) chloride hexahydrate which is pink in color reacts with water, it results in a pink-colored solution.

The color of dry cobalt (II) chloride is blue in color.

d.

Interpretation Introduction

Interpretation: To calculate the percent by mass of water in the hexahydrate.

Concept Introduction: The percent mass can be calculated as the ratio of the mass of the chemical to the mass of the total compound multiplied by 100.

Answer to Problem 89A

The percent of mass by water is $45.40\%$ .

Explanation of Solution

The mass of 6 moles of water can be calculated as follows:

  $\begin{array}{l}\text{6}\left[\left(2\times 1.0\text{g}\right)+16.0\text{ g}\right]\\ =108.0\text{ g}\end{array}$

The molar mass of cobalt (II) chloride is given as follows:

  $\begin{array}{l}\text{58}\text{.9}\text{g}+\left(2\times 35.5\text{g}\right)+108.0\text{g}\\ =\text{237}\text{.9 g}\end{array}$

The percent by mass of water in the hexahydrate can be calculated as follows:

  $\begin{array}{c}{\text{\% by mass H}}_2\text{O}=\frac{108.0\text{g}}{237.9\text{g}}\times 100\%\\ =45.40\%\end{array}$

e.

Interpretation Introduction

Interpretation: To give the use of cobalt (II) chloride test paper.

Concept Introduction: The color of cobalt chloride test paper is blue in color. The cobalt (II) chloride hexahydrate is heated it breaks the water of hydration and results in cobalt (II) chloride.

Answer to Problem 89A

The use of cobalt (II) chloride test paper is best for water or water vapors.

Explanation of Solution

The color of cobalt chloride test paper is blue in color. The cobalt (II) chloride hexahydrate is heated it breaks the water of hydration and results in cobalt (II) chloride.

  ${\text{CoCl}}_{\text{2}}{\text{.6H}}_{\text{2}}\text{O}\stackrel{\text{Heat}}{\to }{\text{CoCl}}_{\text{2}}+{\text{6H}}_{\text{2}}\text{O}$

When cobalt (II) chloride hexahydrate which is pink in color reacts with water, it results in a pink-colored solution.

The use of cobalt (II) chloride test paper is best for water or water vapors.