Chapter 21, Problem 21.27QP

(a)

Interpretation Introduction

Interpretation:

The given reaction has to be completed and balanced.

Concept Introduction:

Balanced equation:

• It is a chemical equation in which the number of each type of atoms will be equal in the stoichiometric ratios on both the sides of the equation.
• The concept of writing a balanced chemical equation is based on the law of conversion of mass
• According to the law of conversion of mass, in a chemical reaction the mass of total amount of the product should be equal to the total mass of the reactants.
• First write the reaction from the given information.
• Then count the number of atoms of each element in reactants as well as products.
• Insert some positive integers as coefficients of reactants as well as products in order to get the equal number of all elements on both sides of the equation.

Explanation of Solution

The given chemical equation is:

$\text{K}\left(\text{s}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)\stackrel{}{\to }$

The complete equation is:

$\text{K}\left(\text{s}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)\stackrel{}{\to }\text{KOH}\left(\text{aq}\right)+{\text{H}}_{\text{2}}\left(\text{g}\right)$

It is an unbalanced equation.

This unbalanced equation is balanced as instructed below:

• The balancing equation should be started with the element which is being with the coefficient 1 on either side.
• So starting with oxygen, since there is only one oxygen atom both sides. Thus, oxygen is balanced.
• Then there is only one potassium atom on both sides. So, it is also balanced.
• But the hydrogen atoms are not balanced on either side. On the right side, there are three hydrogen atoms whereas on the left side there are only two hydrogen atoms.
• It can be balanced by entering the coefficient of water molecule as 2, so that there are four hydrogen atoms on the left side. To balance this, 2 hydrogen atoms are need on the right side which can be achieved by entering the coefficient of $\text{KOH}$ as 2 which unbalances the potassium on left side. It can be balanced by entering its coefficient as 2.  Now then all the atoms are balanced.

So, the balanced equation is:

$\text{2K}\left(\text{s}\right)+2{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)\stackrel{}{\to }2\text{KOH}\left(\text{aq}\right)+{\text{H}}_{\text{2}}\left(\text{g}\right)$

The elemental abbreviations in the balanced equation:

$\text{K}$- Potassium reacts in its solid phase.

${\text{H}}_{\text{2}}\text{O}$- Water reacts in its liquid phase.

$\text{KOH}$-Potassium hydroxide is formed in the aqueous phase.

${\text{H}}_{\text{2}}$-Hydrogen molecule is formed in the gaseous phase.

(b)

Interpretation Introduction

Interpretation: The given reaction has to be completed and balanced.

Concept Introduction:

Balanced equation:

• It is a chemical equation in which the number of each type of atoms will be equal in the stoichiometric ratios on both the sides of the equation.
• The concept of writing a balanced chemical equation is based on the law of conversion of mass
• According to the law of conversion of mass, in a chemical reaction the mass of total amount of the product should be equal to the total mass of the reactants.
• First write the reaction from the given information.
• Then count the number of atoms of each element in reactants as well as products.
• Insert some positive integers as coefficients of reactants as well as products in order to get the equal number of all elements on both sides of the equation.

Explanation of Solution

The given chemical equation is:

$\text{NaH}\left(\text{s}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)\stackrel{}{\to }$

The complete equation is:

$\text{NaH}\left(\text{s}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)\stackrel{}{\to }\text{NaOH}\left(\text{aq}\right)+{\text{H}}_{\text{2}}\left(\text{g}\right)$

It is a balanced equation.

In this case, the complete form of the equation itself is in the balanced form. So there is no need of balancing the equation further.

So, the balanced equation is:

$\text{NaH}\left(\text{s}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)\stackrel{}{\to }\text{NaOH}\left(\text{aq}\right)+{\text{H}}_{\text{2}}\left(\text{g}\right)$

The elemental abbreviations in the balanced equation:

$\text{NaH}$- Sodium hydride reacts in its solid phase.

${\text{H}}_{\text{2}}\text{O}$- Water reacts in its liquid phase.

$\text{NaOH}$- Sodium hydroxide is formed in the aqueous phase.

${\text{H}}_{\text{2}}$-Hydrogen molecule is formed in the gaseous phase.

(c)

Interpretation Introduction

Interpretation: The given reaction has to be completed and balanced.

Concept Introduction:

Balanced equation:

• It is a chemical equation in which the number of each type of atoms will be equal in the stoichiometric ratios on both the sides of the equation.
• The concept of writing a balanced chemical equation is based on the law of conversion of mass
• According to the law of conversion of mass, in a chemical reaction the mass of total amount of the product should be equal to the total mass of the reactants.
• First write the reaction from the given information.
• Then count the number of atoms of each element in reactants as well as products.
• Insert some positive integers as coefficients of reactants as well as products in order to get the equal number of all elements on both sides of the equation.

Explanation of Solution

The given chemical equation is:

$\text{Na}\left(\text{s}\right)+{\text{O}}_2\left(\text{g}\right)\stackrel{}{\to }$

The complete equation is:

$\text{Na}\left(\text{s}\right)+{\text{O}}_2\left(\text{g}\right)\stackrel{}{\to }{\text{Na}}_2{\text{O}}_2\left(\text{s}\right)$

It is an unbalanced equation.

This unbalanced equation is balanced as instructed below:

• In the unbalanced equation, the oxygen atoms are balanced on both the sides. Only the sodium atoms are needed to be balanced.
• There are two sodium atoms on the right but only one sodium atom on the left. So, the by entering the coefficient of sodium atom as 2 on the left side, then it balances the sodium atoms on the left side. Now then all the atoms are balanced.

So, the balanced equation is:

$\text{2Na}\left(\text{s}\right)+{\text{O}}_2\left(\text{g}\right)\stackrel{}{\to }{\text{Na}}_2{\text{O}}_2\left(\text{s}\right)$

The elemental abbreviations in the balanced equation:

$\text{Na}$- Sodium reacts in its solid phase.

${\text{O}}_2$- Oxygen reacts in its gaseous phase.

${\text{Na}}_2{\text{O}}_2$- Sodium peroxide is formed in the solid phase.

(d)

Interpretation Introduction

Interpretation: The given reaction has to be completed and balanced.

Concept Introduction:

Balanced equation:

• It is a chemical equation in which the number of each type of atoms will be equal in the stoichiometric ratios on both the sides of the equation.
• The concept of writing a balanced chemical equation is based on the law of conversion of mass
• According to the law of conversion of mass, in a chemical reaction the mass of total amount of the product should be equal to the total mass of the reactants.
• First write the reaction from the given information.
• Then count the number of atoms of each element in reactants as well as products.
• Insert some positive integers as coefficients of reactants as well as products in order to get the equal number of all elements on both sides of the equation.

Explanation of Solution

The given chemical equation is:

$\text{K}\left(\text{s}\right)+{\text{O}}_2\left(\text{g}\right)\stackrel{}{\to }$

The complete equation is:

$\text{K}\left(\text{s}\right)+{\text{O}}_2\left(\text{g}\right)\stackrel{}{\to }{\text{KO}}_2\left(\text{s}\right)$

It is a balanced equation.

In this case, the complete form of the equation itself is in the balanced form. So there is no need of balancing the equation further.

So, the balanced equation is:

$\text{K}\left(\text{s}\right)+{\text{O}}_2\left(\text{g}\right)\stackrel{}{\to }{\text{KO}}_2\left(\text{s}\right)$

In this balanced equation,

• Potassium is balanced on both the sides by 1 mole.
• Oxygen is balanced on both the sides by 2moles.

The elemental abbreviations in the balanced equation:

$\text{K}$- Sodium reacts in its solid phase.

${\text{O}}_2$- Oxygen reacts in its gaseous phase.

${\text{KO}}_2$- Potassium peroxide is formed in the solid phase.