Chapter 3, Problem 3.4P

(a)

Interpretation Introduction

Interpretation:

Chemical equation given below has to be balanced.

    ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}(aq)+\text{KOH}(aq)\to {\text{K}}_{\text{2}}{\text{SO}}_{\text{4}}(aq)+{\text{H}}_{\text{2}}\text{O}(l)$

Concept Introduction:

Chemical reaction is represented in short form by using the molecular formulas of products and reactants in which an arrow is present between reactants and products is known as chemical equation.  Atoms are neither created nor destroyed in any chemical reaction.  Therefore, the resulting chemical equation written for the chemical reaction should also be balanced.

Steps followed to obtain balanced chemical equation:

• Chemical formulas of the products and reactants are written.  Individual reactants and products are separated using plus sign while the reactants are separated from products by an arrow.
• Elements that appear only once on the reactant side and product side is balanced first.  Subscript should not be changed in chemical formula while balancing coefficients can be added until the total number of atoms of an element becomes equal on reactant and product side.
• Other elements present also balanced in the same way by adding balancing coefficients.
• Final check has to be performed in order to check that each element that is present in the chemical equation is balanced.
• Symbols have to be added for solids, liquids gases and aqueous solutions to indicate the physical state of the known reactants and products.

Explanation of Solution

Chemical equation given is shown below.

    ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}(aq)+\text{KOH}(aq)\to {\text{K}}_{\text{2}}{\text{SO}}_{\text{4}}(aq)+{\text{H}}_{\text{2}}\text{O}(l)$

Above chemical equation is not balanced.  There is one potassium atom on the reactant side while there are two potassium atoms on the product side.  Adding coefficient $2$ before $\text{KOH}$ in the reactant side balances the potassium atoms on both side of the equation.  The chemical equation obtained is given as shown below.

    ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}(aq)+2\text{KOH}(aq)\to {\text{K}}_{\text{2}}{\text{SO}}_{\text{4}}(aq)+{\text{H}}_{\text{2}}\text{O}(l)(notbalanced)$

In the above equation, there are four hydrogen atoms on the reactant side while there are only two hydrogen atoms on the product side.  Adding coefficient $2$ before ${\text{H}}_{\text{2}}\text{O}$ balances out the hydrogen atoms on both sides of the equation.  The balanced chemical equation obtained is given as shown below.

    ${\text{H}}_{\text{2}}{\text{SO}}_{\text{4}}(aq)+2\text{KOH}(aq)\to {\text{K}}_{\text{2}}{\text{SO}}_{\text{4}}(aq)+2{\text{H}}_{\text{2}}\text{O}(l)(balanced)$

(b)

Interpretation Introduction

Interpretation:

Chemical equation given below has to be balanced.

    ${\text{Li}}_{\text{3}}\text{N}(s)+{\text{H}}_{\text{2}}\text{O}(l)\to \text{LiOH}(aq)+{\text{NH}}_{\text{3}}(g)$

Concept Introduction:

Refer part (a).

Explanation of Solution

Chemical equation given is shown below.

    ${\text{Li}}_{\text{3}}\text{N}(s)+{\text{H}}_{\text{2}}\text{O}(l)\to \text{LiOH}(aq)+{\text{NH}}_{\text{3}}(g)$

Above chemical equation is not balanced.  There are three lithium atoms on the reactant side while there is only one lithium atom on the product side.  Adding coefficient $3$ before $\text{LiOH}$ on the product side balances the lithium atoms on both sides.  This chemical equation obtained is given as shown below.

    ${\text{Li}}_{\text{3}}\text{N}(s)+{\text{H}}_{\text{2}}\text{O}(l)\to 3\text{LiOH}(aq)+{\text{NH}}_{\text{3}}(g)(notbalanced)$

In the above equation, there are two hydrogen atoms on the reactant side while in the product side a total of six hydrogen atoms are present.  Adding coefficient $3$ before ${\text{H}}_{\text{2}}\text{O}$ on the reactant side balances the hydrogen atoms on both sides.  This step balances the other atoms also.  The balanced chemical equation obtained is shown as given below.

    ${\text{Li}}_{\text{3}}\text{N}(s)+3{\text{H}}_{\text{2}}\text{O}(l)\to 3\text{LiOH}(aq)+{\text{NH}}_{\text{3}}(g)(balanced)$

(c)

Interpretation Introduction

Interpretation:

Chemical equation given below has to be balanced.

    ${\text{Al}}_{\text{4}}{\text{C}}_{\text{3}}(s)+\text{HCl}(aq)\to {\text{AlCl}}_{\text{3}}(aq)+{\text{CH}}_{\text{4}}(g)$

Concept Introduction:

Refer part (a).

Explanation of Solution

Chemical equation given is shown below.

    ${\text{Al}}_{\text{4}}{\text{C}}_{\text{3}}(s)+\text{HCl}(aq)\to {\text{AlCl}}_{\text{3}}(aq)+{\text{CH}}_{\text{4}}(g)$

Above chemical equation is not balanced.  There are four aluminium atoms on the reactant side but in the product side there is only one aluminium atom.  Adding coefficient $4$ before ${\text{AlCl}}_{\text{3}}$ balances the aluminium atoms on both sides of the equation.  The chemical equation obtained is given below.

    ${\text{Al}}_{\text{4}}{\text{C}}_{\text{3}}(s)+\text{HCl}(aq)\to 4{\text{AlCl}}_{\text{3}}(aq)+{\text{CH}}_{\text{4}}(g)(notbalanced)$

In the above chemical equation, there is only one chlorine atom on the reactant side while in the product side there are twelve chlorine atoms.  Adding coefficient $12$ before $\text{HCl}$ on the reactant side balances the chlorine atoms on both sides of the equation.  The chemical equation obtained is shown as given below.

    ${\text{Al}}_{\text{4}}{\text{C}}_{\text{3}}(s)+12\text{HCl}(aq)\to 4{\text{AlCl}}_{\text{3}}(aq)+{\text{CH}}_{\text{4}}(g)(notbalanced)$

In the above chemical equation, there are twelve hydrogen atoms in the reactant side while in the product side there are four hydrogen atoms.  Adding coefficient $3$ before ${\text{CH}}_{\text{4}}$ on the product side balances the hydrogen atoms on both sides.  This step balances the other atoms also.  The balanced chemical equation obtained is given as shown below.

    ${\text{Al}}_{\text{4}}{\text{C}}_{\text{3}}(s)+12\text{HCl}(aq)\to 4{\text{AlCl}}_{\text{3}}(aq)+3{\text{CH}}_{\text{4}}(g)(balanced)$

(d)

Interpretation Introduction

Interpretation:

Chemical equation given below has to be balanced.

    $\text{ZnS}(s)+\text{HBr}(aq)\to {\text{ZnBr}}_{\text{2}}(aq)+{\text{H}}_{\text{2}}\text{S}(g)$

Concept Introduction:

Refer part (a).

Explanation of Solution

Chemical equation given is shown below.

    $\text{ZnS}(s)+\text{HBr}(aq)\to {\text{ZnBr}}_{\text{2}}(aq)+{\text{H}}_{\text{2}}\text{S}(g)$

Above chemical equation is not balanced.  There is one bromine atom on the reactant side and two bromine atoms on the product side.  Adding coefficient $2$ before $\text{HBr}$ balances the bromine atoms on both sides of the equation.  This step balances the other atoms also.  The balanced chemical equation obtained is given as shown below.

    $\text{ZnS}(s)+2\text{HBr}(aq)\to {\text{ZnBr}}_{\text{2}}(aq)+{\text{H}}_{\text{2}}\text{S}(g)(balanced)$