Chapter 11, Problem 48A

(a)

Interpretation Introduction

Interpretation:

A balanced chemical equation when chlorine gas is bubbled through a solution of potassium iodide which gives elemental iodine and a solution of potassium chloride is to be written.

Concept Introduction :

A balanced equation shows the particles involved in the reaction with respect to mass and charge. In a balanced chemical equation, there are equal number of atoms of the same elements on both sides of the reaction arrow.

Answer to Problem 48A

The balanced equation is ${\text{Cl}}_2\left(\text{g}\right)+2\text{KI}\left(\text{aq}\right)\to {\text{I}}_2\left(\text{s}\right)+2\text{KCl}\left(\text{aq}\right)$ .

Explanation of Solution

When chlorine gas is bubbled through a solution of potassium iodide which gives elemental iodine and a solution of potassium chloride then the equations formed are as:

  ${\text{Cl}}_2\left(\text{g}\right)+\text{KI}\left(\text{aq}\right)\to {\text{I}}_2\left(\text{s}\right)+\text{KCl}\left(\text{aq}\right)$

Where $\text{Cl}$ is for chlorine, $\text{KI}$ is for potassium iodide, ${\text{I}}_2$ is for elemental iodine, and $\text{KCl}$ is for potassium chloride.

According to the law of conservation of mass, it is stated that the mass of the product is equal to the mass of reactants.

So, the above equation is unbalanced as there are 2 iodine atoms on the right side and only 1 on the left side, thus a coefficient of 2 must be put in front of potassium iodide and there are 2 chlorine on right but 1 chlorine on left so a coefficient of 2 must be put in front of potassium chloride for making the equation balanced as shown below:

  ${\text{Cl}}_2\left(\text{g}\right)+2\text{KI}\left(\text{aq}\right)\to {\text{I}}_2\left(\text{s}\right)+2\text{KCl}\left(\text{aq}\right)$

(b)

Interpretation Introduction

Interpretation:

A balanced chemical equation when bubbles of hydrogen gas and aqueous iron(III) are produced when metallic iron is dropped into hydrochloric acid is to be written.

Concept Introduction :

According to the law of conservation of mass, it is stated that the mass of the product is equal to the mass of reactants. In a balanced chemical equation, there are an equal number of atoms of the same elements on both sides of the reaction arrow.

Answer to Problem 48A

The balanced equation is $\text{2Fe}\left(\text{s}\right)+6\text{HCl}\left(\text{aq}\right)\to 3{\text{H}}_2\left(\text{g}\right)+2\text{FeCl}\left(\text{aq}\right)$ .

Explanation of Solution

Bubbles of hydrogen gas and aqueous iron(III) are produced when metallic iron is dropped into hydrochloric acid then the equation formed in words is as:

metallic iron + hydrochloric acid gives hydrogen gas + aqueous iron(III) chloride

The symbol equation is as:

  $\text{Fe}\left(\text{s}\right)+\text{HCl}\left(\text{aq}\right)\to {\text{H}}_2\left(\text{g}\right)+\text{FeCl}\left(\text{aq}\right)$

Where $\text{Fe}$ is for metallic iron, $\text{HCl}$ is for hydrochloric acid, ${\text{H}}_2$ is for hydrogen gas, and $\text{FeCl}\left(\text{aq}\right)$ is for aqueous iron (III) chloride.

The above equation is unbalanced as:

• There are 3 chlorine atoms on the right side and 1 on the left side, thus, a coefficient of 3 must be put in front of hydrogen chloride.

• There are 3 hydrogen atoms on left but 2 on the right so a coefficient of 3 must be put in front of hydrogen and the coefficient of 3 is changed to 6 in front of hydrogen chloride for making the hydrogen atoms balanced.

Hence the balanced equation is as $\text{2Fe}\left(\text{s}\right)+6\text{HCl}\left(\text{aq}\right)\to 3{\text{H}}_2\left(\text{g}\right)+2\text{FeCl}\left(\text{aq}\right)$ .

(c)

Interpretation Introduction

Interpretation:

A balanced chemical equation must be written when solid tetraphosphorus decaoxide reacts with water to produce phosphoric acid.

Concept Introduction :

A balanced equation shows the particles involved in the reaction with respect to mass and charge. In a balanced chemical equation, there are equal number of atoms of the same elements on both sides of the reaction arrow.

Answer to Problem 48A

The balanced equation is ${\text{P}}_4{\text{O}}_{10}\left(\text{s}\right)+6{\text{H}}_2\text{O}\left(\text{l}\right)\to 4{\text{H}}_3{\text{PO}}_4\left(\text{aq}\right)$ .

Explanation of Solution

When solid tetraphosphorus decaoxide reacts with water to produce phosphoric acid then the equation formed in words is as:

solid tetraphosphorus decaoxide + water gives phosphoric acid

The symbol equation is as:

  ${\text{P}}_4{\text{O}}_{10}\left(\text{s}\right)+{\text{H}}_2\text{O}\left(\text{l}\right)\to {\text{H}}_3{\text{PO}}_4\left(\text{aq}\right)$

Where ${\text{P}}_4{\text{O}}_{10}\left(\text{s}\right)$ is for solid tetraphosphorus, ${\text{H}}_2\text{O}\left(\text{l}\right)$ is for water, ${\text{H}}_3{\text{PO}}_4\left(\text{aq}\right)$ is for phosphoric acid.

The above equation is unbalanced as:

• There is 1 P on the right side and 4 on the left side, thus, a coefficient of 4 must be put in front of phosphoric acid and there are 2 hydrogen atoms on left but 12 on the right so a coefficient of 6 must be put in front of the water.

Hence, the balanced equation is as ${\text{P}}_4{\text{O}}_{10}\left(\text{s}\right)+6{\text{H}}_2\text{O}\left(\text{l}\right)\to 4{\text{H}}_3{\text{PO}}_4\left(\text{aq}\right)$ .