Chapter 11, Problem 59A

(a)

Interpretation Introduction

Interpretation:

The balanced chemical equation needs to be determined when sodium iodide reacts with phosphoric acid.

Concept Introduction :

An exchange of positive ions between the two aqueous solutions AB + CD which results in CB + AD is the general form of the double replacement reaction.

Answer to Problem 59A

The balanced chemical equation is $\text{3NaI}+{\text{H}}_3{\text{PO}}_4\to {\text{Na}}_{\text{3}}{\text{PO}}_{\text{4}}+3\text{HI}$ .

Explanation of Solution

Step 1:

When sodium iodide $\text{NaI}$ reacts with phosphoric acid ${\text{H}}_3{\text{PO}}_4$ a double replacement reaction occurs so one follows the form of $\text{AB}+\text{CD}\to \text{CB}+\text{AD}$ where $\text{AB}=\text{NaI},{\text{CD = H}}_3{\text{PO}}_4$ so the result is as $\text{CB + AD}$ .

Here $\text{CB}={\text{Na}}_{\text{3}}{\text{PO}}_{\text{4}}\text{,AD = HI}$ .

Step 2:

As the equation is unbalanced, since there are 3 H on the left side and 1 H on the right side, so, coefficient 3 is put in front of HI and the balanced equation will be:

  $\text{3NaI}+{\text{H}}_3{\text{PO}}_4\to {\text{Na}}_{\text{3}}{\text{PO}}_{\text{4}}+3\text{HI}$

(b)

Interpretation Introduction

Interpretation:

The balanced chemical equation needs to be determined when potassium oxide reacts with water.

Concept Introduction :

A reaction in which a single product is formed when multiple reactants are combined is called a combination reaction.

Answer to Problem 59A

The balanced chemical equation is ${\text{K}}_2\text{O}+{\text{H}}_2\text{O}\to 2\text{KOH}$ .

Explanation of Solution

When potassium oxide reacts with water then the equation is ${\text{K}}_2\text{O}+{\text{H}}_2\text{O}\to$ which is a combination reaction where two reactants join together to form one product, so the equation becomes as:

  ${\text{K}}_2\text{O}+{\text{H}}_2\text{O}\to \text{KOH}$ .

This is an unbalanced equation since there are 2 K on the left and 1 K on the right, so, the coefficients are adjusted so that there are the same number of reactants and products on both sides to form a single compound.

A coefficient of 2 is put in front of KOH to make a balance equation.

Hence, the balanced chemical equation is ${\text{K}}_2\text{O}+{\text{H}}_2\text{O}\to 2\text{KOH}$ .

(c)

Interpretation Introduction

Interpretation:

The balanced chemical equation needs to be determined when sulfuric acid is heated, and it produces water, oxygen, and sulfur dioxide.

Concept Introduction :

A chemical reaction in which two or more products are given by one reactant is called a decomposition reaction and the general form of such reaction is $\text{AB}\to \text{A}+\text{B}$ .

Answer to Problem 59A

The balanced chemical equation is ${\text{2H}}_2{\text{SO}}_4\to {\text{2H}}_2{\text{O + O}}_2{\text{+ SO}}_2$ .

Explanation of Solution

When sulfuric acid is heated, it produces water, oxygen, and sulfur dioxide, then the equation is ${\text{H}}_2{\text{SO}}_4\to {\text{H}}_2{\text{O + O}}_2{\text{+ SO}}_2$ which is an unbalanced equation since there are 4 O on the left and 5 O on right, so the coefficients are adjusted so that there are same number of the reactants and products.

Hence, the balanced chemical equation is ${\text{2H}}_2{\text{SO}}_4\to {\text{2H}}_2{\text{O + O}}_2{\text{+ SO}}_2$ .

(d)

Interpretation Introduction

Interpretation:

The balanced chemical equation needs to be determined when aluminum reacts with sulfuric acid.

Concept Introduction :

A chemical reaction where two or more products are given by one reactant is called a decomposition reaction and the general form of such reaction is $\text{AB}\to \text{A}+\text{B}$ .

Answer to Problem 59A

The balanced chemical equation is $\text{2Al}\left(\text{s}\right)+3{\text{H}}_2{\text{SO}}_4\left(\text{aq}\right)\to {\text{Al}}_2{\left({\text{SO}}_{\text{4}}\right)}_3\left(\text{aq}\right){\text{+ 3H}}_2\left(g\right)$ .

Explanation of Solution

When aluminum reacts with sulfuric acid, then the equation is $\text{2Al}\left(\text{s}\right)+3{\text{H}}_2{\text{SO}}_4\left(\text{aq}\right)$ which is a decomposition reaction.

Hence, the balanced chemical equation is $\text{2Al}\left(\text{s}\right)+3{\text{H}}_2{\text{SO}}_4\left(\text{aq}\right)\to {\text{Al}}_2{\left({\text{SO}}_{\text{4}}\right)}_3\left(\text{aq}\right){\text{+ 3H}}_2\left(g\right)$ .

(e)

Interpretation Introduction

Interpretation:

The balanced chemical equation needs to be determined when pentane $\left({\text{C}}_{\text{5}}{\text{H}}_{\text{12}}\right)$ reacts with oxygen.

Concept Introduction :

A chemical reaction where two or more products are given by one reactant is called a decomposition reaction and the general form of such reaction is $\text{AB}\to \text{A}+\text{B}$ .

Answer to Problem 59A

The balanced chemical equation is ${\text{C}}_{\text{5}}{\text{H}}_{\text{12}}{\text{+ 8O}}_{\text{2}}\to {\text{5CO}}_{\text{2}}{\text{+ 6H}}_{\text{2}}\text{O}$ .

Explanation of Solution

When pentane reacts with oxygen, then the equation is ${\text{C}}_{\text{5}}{\text{H}}_{\text{12}}{\text{+ O}}_{\text{2}}$ which is a combustion reaction.

Hence, the balanced chemical equation is ${\text{C}}_{\text{5}}{\text{H}}_{\text{12}}{\text{+ 8O}}_{\text{2}}\to {\text{5CO}}_{\text{2}}{\text{+ 6H}}_{\text{2}}\text{O}$ .