Chapter 8, Problem 3PE

(a)

Interpretation Introduction

Interpretation:

The equation has to be balanced and the type of reaction has to be given.

The given equation is,

  ${\text{H}}_{\text{2}}{\text{+O}}_{\text{2}}\stackrel{}{\to }{\text{H}}_{\text{2}}\text{O}$

Concept Introduction:

Combination reactions/Synthesis reactions:  In these reactions, the reactant combines to form a single product.  This type of reaction occurs between either two elements, an element and a compound or two compounds.  It is recognized easily because it involves two reactants and only a single product.

Example:  The product for the combination reaction of magnesium oxide and carbon dioxide is magnesium carbonate.  The completed equation is,

  $\text{MgO}\left(\text{s}\right){\text{+CO}}_{\text{2}}\left(\text{g}\right)\stackrel{}{\to }{\text{MgCO}}_{\text{3}}\left(\text{s}\right)$

Single displacement reactions:  A reaction where an element in a compound is replaced by another element is called single displacement reaction or a substitution reaction.  It generally involves between a dilute solution of an acid and a metal.

Example:  The product for the single displacement reaction of reaction of zinc and hydrogen bromide is zinc bromide and hydrogen.  The balanced reaction is,

  $\text{Zn}\left(\text{s}\right)\text{+2HBr}\left(\text{aq}\right)\stackrel{}{\to }{\text{ZnBr}}_{\text{2}}\left(\text{s}\right){\text{+H}}_{\text{2}}\left(\text{g}\right)$

Double displacement reactions:  This type of reactions occurs when the cation and the anions switch between two reactants to form new products.  In order for the reaction to occur, one of the products is usually a solid precipitate, a gas or a molecular compound.

Example:  The product of the reaction between nitric acid and calcium sulphide is gaseous hydrogen sulphide and calcium nitrate.  The completed equation is,

  $\text{CaS}\left(\text{s}\right){\text{+2HNO}}_{\text{3}}\left(\text{aq}\right)\stackrel{}{\to }\text{Ca}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}\left(\text{aq}\right){\text{+H}}_{\text{2}}\text{S}\left(\text{g}\right)$

Decomposition reactions:  Decomposition reactions are the opposite of a combination reaction because decomposition reaction involves the breaking apart of a substance into simpler substances.  Such a reaction is easy to recognize because there is one reactant and more than one product.

Example:  The reaction of sodium chlorate to sodium chloride and oxygen is decomposition reaction.  The balanced reaction is,

  ${\text{2NaClO}}_{\text{3}}\left(\text{s}\right)\stackrel{}{\to }\text{2NaCl}\left(\text{s}\right){\text{+3O}}_{\text{2}}\left(\text{g}\right)$

Answer to Problem 3PE

The balanced equation is

  ${\text{2H}}_{\text{2}}{\text{+O}}_{\text{2}}\stackrel{}{\to }{\text{2H}}_{\text{2}}\text{O}$

The reaction between hydrogen and oxygen to form water is synthesis reaction.

Explanation of Solution

Hydrogen reacts with oxygen to form water.  This reaction is an example of synthesis (or) combination reaction because two reactants form a single product.  The chemical reaction is,

  ${\text{H}}_{\text{2}}{\text{+O}}_{\text{2}}\stackrel{}{\to }{\text{H}}_{\text{2}}\text{O}$

The above reaction is unbalanced.  The balanced equation is

  ${\text{2H}}_{\text{2}}{\text{+O}}_{\text{2}}\stackrel{}{\to }{\text{2H}}_{\text{2}}\text{O}$

(b)

Interpretation Introduction

Interpretation:

The equation has to be balanced and the type of reaction has to be given.

The given equation is,

  ${\text{N}}_{\text{2}}{\text{H}}_{\text{4}}\left(\text{l}\right)\stackrel{}{\to }{\text{NH}}_{\text{3}}\left(\text{g}\right){\text{+N}}_{\text{2}}\left(\text{g}\right)$

Concept Introduction:

Refer to part (a).

Answer to Problem 3PE

The balanced equation is,

  ${\text{3N}}_{\text{2}}{\text{H}}_{\text{4}}\left(\text{l}\right)\stackrel{}{\to }{\text{4NH}}_{\text{3}}\left(\text{g}\right){\text{+N}}_{\text{2}}\left(\text{g}\right)$

The reaction of hydrazine to give ammonia gas and nitrogen gas is a decomposition reaction.

Explanation of Solution

The reaction of hydrazine to give ammonia gas and nitrogen gas is a decomposition reaction because a single reactant gives more than one product.  The chemical equation is,

  ${\text{N}}_{\text{2}}{\text{H}}_{\text{4}}\left(\text{l}\right)\stackrel{}{\to }{\text{NH}}_{\text{3}}\left(\text{g}\right){\text{+N}}_{\text{2}}\left(\text{g}\right)$

The above reaction is unbalanced.  The balanced equation is,

  ${\text{3N}}_{\text{2}}{\text{H}}_{\text{4}}\left(\text{l}\right)\stackrel{}{\to }{\text{4NH}}_{\text{3}}\left(\text{g}\right){\text{+N}}_{\text{2}}\left(\text{g}\right)$

(c)

Interpretation Introduction

Interpretation:

The equation has to be balanced and the type of reaction has to be given.

The given equation is,

  ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}\text{+NaOH}\stackrel{}{\to }{\text{H}}_{\text{2}}{\text{O+Na}}_{\text{2}}{\text{SO}}_{\text{4}}$

Concept Introduction:

Refer to part (a).

Answer to Problem 3PE

The balanced equation is,

  ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}\text{+2NaOH}\stackrel{}{\to }{\text{2H}}_{\text{2}}{\text{O+Na}}_{\text{2}}{\text{SO}}_{\text{4}}$

The reaction of sulfuric acid with sodium hydroxide to give water and sodium sulfate is a double displacement reaction.

Explanation of Solution

The reaction of sulfuric acid with sodium hydroxide to give water and sodium sulfate is a double displacement reaction because the two cations are interchange to give products.  The chemical equation is,

  ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}\text{+NaOH}\stackrel{}{\to }{\text{H}}_{\text{2}}{\text{O+Na}}_{\text{2}}{\text{SO}}_{\text{4}}$

The above reaction is unbalanced.  The balanced equation is,

  ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}\text{+2NaOH}\stackrel{}{\to }{\text{2H}}_{\text{2}}{\text{O+Na}}_{\text{2}}{\text{SO}}_{\text{4}}$

(d)

Interpretation Introduction

Interpretation:

The equation has to be balanced and the type of reaction has to be given.

The given equation is,

  ${\text{Al}}_{\text{2}}{\left({\text{CO}}_{\text{3}}\right)}_{\text{3}}\stackrel{\text{Δ}}{\to }{\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}{\text{+CO}}_{\text{2}}$

Concept Introduction:

Refer to part (a).

Answer to Problem 3PE

The balanced equation is,

  ${\text{Al}}_{\text{2}}{\left({\text{CO}}_{\text{3}}\right)}_{\text{3}}\stackrel{\text{Δ}}{\to }{\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}{\text{+3CO}}_{\text{2}}$

The reaction of aluminum carbonate to give aluminum oxide and carbon dioxide is a decomposition reaction.

Explanation of Solution

The reaction of aluminum carbonate to give aluminum oxide and carbon dioxide is a decomposition reaction because a single reactant gives more than one product.  The chemical equation is,

  ${\text{Al}}_{\text{2}}{\left({\text{CO}}_{\text{3}}\right)}_{\text{3}}\stackrel{\text{Δ}}{\to }{\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}{\text{+CO}}_{\text{2}}$

The above reaction is unbalanced.  The balanced equation is,

  ${\text{Al}}_{\text{2}}{\left({\text{CO}}_{\text{3}}\right)}_{\text{3}}\stackrel{\text{Δ}}{\to }{\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}{\text{+3CO}}_{\text{2}}$

(e)

Interpretation Introduction

Interpretation:

The equation has to be balanced and the type of reaction has to be given.

The given equation is,

  ${\text{NH}}_{\text{4}}{\text{I+Cl}}_{\text{2}}\stackrel{}{\to }{\text{NH}}_{\text{4}}{\text{Cl+I}}_{\text{2}}$

Concept Introduction:

Refer to part (a).

Answer to Problem 3PE

The balanced equation is,

  ${\text{2NH}}_{\text{4}}{\text{I+Cl}}_{\text{2}}\stackrel{}{\to }{\text{2NH}}_{\text{4}}{\text{Cl+I}}_{\text{2}}$

The reaction of ammonium iodide with chlorine to give ammonium chloride with evolution of iodine is a single displacement reaction.

Explanation of Solution

The reaction of ammonium iodide with chlorine to give ammonium chloride with evolution of iodine is a single displacement reaction because according to the activity series, chlorine is more reactive than iodine, therefore it will displace iodine from ammonium iodide.  The chemical reaction is,

  ${\text{NH}}_{\text{4}}{\text{I+Cl}}_{\text{2}}\stackrel{}{\to }{\text{NH}}_{\text{4}}{\text{Cl+I}}_{\text{2}}$

The above reaction is unbalanced.  The balanced equation is,

  ${\text{2NH}}_{\text{4}}{\text{I+Cl}}_{\text{2}}\stackrel{}{\to }{\text{2NH}}_{\text{4}}{\text{Cl+I}}_{\text{2}}$