Chapter 21, Problem 1E

Interpretation Introduction

(a)

Interpretation:

To determine the chemical equation for the reaction of chlorine gas with cesium.

Concept introduction:

A chemical equation refers to the symbolic representation of a given chemical reaction in the form of formulae and symbols where the product entities are present on the right hand side of the chemical equation while the reactant entities are present on the left hand side of the chemical equation.

Answer to Problem 1E

${\text{2Cs(s)+Cl}}_{\text{2}}\text{(g)}\underset{}{\to }\text{2CsCl(s)}$

Explanation of Solution

Cesium metal is an alkali metal and it has the tendency to form a monovalent cation, namely Cs+ cation. On the other hand, chlorine gas can form chloride ion Cl^-. Both these cation and anion react together to form an ionic compound namely cesium chloride.

The reaction of cesium metal with chlorine gas takes place as shown below in the following chemical equation:

${\text{2Cs(s)+Cl}}_{\text{2}}\text{(g)}\underset{}{\to }\text{2CsCl(s)}$

Cesium chloride is formed as a product in the above reaction.

Interpretation Introduction

(b)

Interpretation:

To determine the chemical equation for the reaction in which sodium peroxide is formed.

Concept introduction:

A chemical equation refers to the symbolic representation of a given chemical reaction in the form of formulae and symbols where the product entities are present on the right hand side of the chemical equation while the reactant entities are present on the left hand side of the chemical equation.

Answer to Problem 1E

${\text{2Na}}_2{\text{O(s)+O}}_{\text{2}}\text{(g)}\underset{}{\to }{\text{2Na}}_2{\text{O}}_2\text{(s)}$

Explanation of Solution

The formation of sodium peroxide is a type of oxidation reaction as it is accompanied by the addition of oxygen molecule to sodium atom.

The formation of sodium peroxide takes place as shown below in the following reaction:

${\text{4Na(s)+O}}_{\text{2}}\text{(g)}\underset{}{\to }{\text{2Na}}_2\text{O(s)}$

This reaction takes place at about 130-200^oC and thereafter sodium oxide that is formed as a product absorbs oxygen in a separate stage and then sodium peroxide is formed.

${\text{2Na}}_2{\text{O(s)+O}}_{\text{2}}\text{(g)}\underset{}{\to }{\text{2Na}}_2{\text{O}}_2\text{(s)}$

Interpretation Introduction

(c)

Interpretation:

To determine the chemical equation for the reaction where thermal decomposition of lithium carbonate takes place.

Concept introduction:

A chemical equation refers to the symbolic representation of a given chemical reaction in the form of formulae and symbols where the product entities are present on the right hand side of the chemical equation while the reactant entities are present on the left hand side of the chemical equation.

Answer to Problem 1E

${\text{Li}}_{\text{2}}{\text{CO}}_{\text{3}}\text{(s)}\stackrel{\text{Δ}}{\to }{\text{Li}}_{\text{2}}{\text{O(s)+CO}}_{\text{2}}\text{(g)}$

Explanation of Solution

Thermal decomposition reactions are those chemical reactions in which the decomposition of a chemical compound is carried out thermally or in the presence of heat. The thermal decomposition of lithium carbonate is as shown below in the following chemical reaction.

${\text{Li}}_{\text{2}}{\text{CO}}_{\text{3}}\text{(s)}\stackrel{\text{Δ}}{\to }{\text{Li}}_{\text{2}}{\text{O(s)+CO}}_{\text{2}}\text{(g)}$

Lithium oxide and carbon dioxide are formed as a product in this reaction.

Interpretation Introduction

(d)

Interpretation:

To determine the chemical equation for the reaction in which sodium sulfate is reduced to sodium sulfide.

Concept introduction:

A chemical equation refers to the symbolic representation of a given chemical reaction in the form of formulae and symbols where the product entities are present on the right hand side of the chemical equation while the reactant entities are present on the left hand side of the chemical equation.

Answer to Problem 1E

${\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}\text{(s)+4C}\stackrel{}{\to }{\text{Na}}_{\text{2}}\text{S(s)+4CO(g)}$

Explanation of Solution

In the reduction of sodium sulfate to sodium sulfide by carbon, sodium sulfate acts as an oxidizing agent as it itself gets reduced to sodium sulfide and oxidizes carbon to form carbon monoxide. Addition of one oxygen atom to carbon indicates that it has been oxidized. On the other hand carbon acts as a reducing agents as it causes reduction of sodium sulfate and itself gets oxidized in the reaction.

Sodium sulfate gets reduced to sodium sulfite in the presence of carbon or coke. The reaction below takes place:

${\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}\text{(s)+4C}\stackrel{}{\to }{\text{Na}}_{\text{2}}\text{S(s)+4CO(g)}$

Carbon monoxide gas is released at the end of the reaction.

Interpretation Introduction

(e)

Interpretation:

To determine the chemical equation for the reaction in which combustion of potassium takes place to form potassium superoxide.

Concept introduction:

A chemical equation refers to the symbolic representation of a given chemical reaction in the form of formulae and symbols where the product entities are present on the righthand side of the chemical equation while the reactant entities are present on the left hand side of the chemical equation.

Answer to Problem 1E

${\text{K(s)+O}}_{\text{2}}\text{(g)}\underset{}{\to }{\text{KO}}_2\text{(s)}$

Explanation of Solution

Combustion reactions are those chemical reactions in which a compound and an oxidant react together and results in the formation of a new product and heat is released at the end of the reaction.

The formation of potassium superoxide takes place by the reaction of molten potassium in which it is burnt in an atmosphere containing oxygen gas. The reaction is shown below:

${\text{K(s)+O}}_{\text{2}}\text{(g)}\underset{}{\to }{\text{KO}}_2\text{(s)}$