Chapter 6, Problem 6.49EP

(a)

Interpretation Introduction

Interpretation:

The chemical equation $Na+H_{2}O\stackrel{}{\to }NaOH+H_2$ has to be balanced.

Concept Introduction:

Statement that uses chemical symbols and formulas instead of words in order to describe the changes that takes place in a chemical reaction is known as chemical equation.  Reactants are the substances that are present in starting of the chemical reaction and it is entered in left side of the chemical equation.  Products are the substance that is obtained from the reactants as a final outcome of the chemical reaction and it is entered in right side of the chemical equation.  In order to write a chemical equation four conventions are used and they are,

• Correct formulas of the reactants are written in left side of chemical equation.
• Correct formulas of products are written in right side of chemical equation.
• An arrow is placed between reactants and products which point towards the products.
• If two or more substances are present in reactant and product, plus sign is used to separate them.

Balanced chemical equation is the one that has equal number of atoms of each element that is involved in the chemical reaction on both sides of the chemical equation.  An unbalanced chemical equation can be balanced by adding coefficients to the equation.  It is a number that is placed in left side of the chemical formula so that it changes the amount only and not the identity.

Answer to Problem 6.49EP

The balanced chemical equation is $2Na+2H_{2}O\stackrel{}{\to }2NaOH+H_2$.

Explanation of Solution

Given chemical equation is $Na+H_{2}O\stackrel{}{\to }NaOH+H_2$.  Looking into the equation, the element that is occurring only once on both sides and the compound that has greater number of atoms has to be started with.  All the atoms except hydrogen is balanced in the given chemical equation.  So start with balancing hydrogen atom.

Balancing $H$ atoms:  There are two $H$ atoms on left side and three $H$ atoms on the right side of the chemical equation.  Placing the coefficient 2 in front of $H_{2}O$ in the left side and coefficient 2 in front of $NaOH$ balances the $H$ atom on both sides.  This makes the sodium atom to be unbalanced.

$Na+2H_{2}O\stackrel{}{\to }2NaOH+H_2$

Balancing $Na$ atoms:  After balancing the $H$ atom, the total number of $Na$ atoms on the right side is 2 and on left side is 1.  Hence, adding coefficient 2 to $Na$ atom on the left side balances the $Na$ atom on both sides.

$2Na+2H_{2}O\stackrel{}{\to }2NaOH+H_2$

The number of atoms of each element on both sides have to be checked and it can be given as shown below,

$\begin{array}{l}\underset{\_}{AtomLeftsideRightside}\\ Na2x1=22x1=2\\ H2x2=42+2=4\\ \underset{\_}{O2x1=22x1=2}\end{array}$

As there are same number of atoms of each element on both sides of the equation, it is said to be a balanced chemical equation.  The balanced chemical equation can be given as,

$2Na+2H_{2}O\stackrel{}{\to }2NaOH+H_2$

Conclusion

Given chemical equation is balanced.

(b)

Interpretation Introduction

Interpretation:

The chemical equation $Na+ZnS{O}_4\stackrel{}{\to }N{a}_{2}S{O}_4+Zn$ has to be balanced.

Concept Introduction:

Statement that uses chemical symbols and formulas instead of words in order to describe the changes that takes place in a chemical reaction is known as chemical equation.  Reactants are the substances that are present in starting of the chemical reaction and it is entered in left side of the chemical equation.  Products are the substance that is obtained from the reactants as a final outcome of the chemical reaction and it is entered in right side of the chemical equation.  In order to write a chemical equation four conventions are used and they are,

• Correct formulas of the reactants are written in left side of chemical equation.
• Correct formulas of products are written in right side of chemical equation.
• An arrow is placed between reactants and products which point towards the products.
• If two or more substances are present in reactant and product, plus sign is used to separate them.

Balanced chemical equation is the one that has equal number of atoms of each element that is involved in the chemical reaction on both sides of the chemical equation.  An unbalanced chemical equation can be balanced by adding coefficients to the equation.  It is a number that is placed in left side of the chemical formula so that it changes the amount only and not the identity.

Answer to Problem 6.49EP

The balanced chemical equation is $2Na+ZnS{O}_4\stackrel{}{\to }N{a}_{2}S{O}_4+Zn$.

Explanation of Solution

Given chemical equation is $Na+ZnS{O}_4\stackrel{}{\to }N{a}_{2}S{O}_4+Zn$.  Looking into the equation, the element that is occurring only once on both sides and the compound that has greater number of atoms has to be started with.  All the atoms except sodium is balanced in the given chemical equation.  So start with balancing sodium atom.

Balancing $Na$ atoms:  There are two $Na$ atoms on right side and one $Na$ atom on the left side of the chemical equation.  Placing the coefficient 2 in front of $Na$ in the left side balances the $Na$ atom on both sides.

$2Na+ZnS{O}_4\stackrel{}{\to }N{a}_{2}S{O}_4+Zn$

The number of atoms of each element on both sides have to be checked and it can be given as shown below,

$\begin{array}{l}\underset{\_}{AtomLeftsideRightside}\\ Na2x1=21x2=2\\ Zn1x1=11x1=1\\ S1x1=11x1=1\\ \underset{\_}{O1x4=41x4=4}\end{array}$

As there are same number of atoms of each element on both sides of the equation, it is said to be a balanced chemical equation.  The balanced chemical equation can be given as,

$2Na+ZnS{O}_4\stackrel{}{\to }N{a}_{2}S{O}_4+Zn$

Conclusion

Given chemical equation is balanced.

(c)

Interpretation Introduction

Interpretation:

The chemical equation $NaBr+C{l}_2\stackrel{}{\to }NaCl+B{r}_2$ has to be balanced.

Concept Introduction:

Statement that uses chemical symbols and formulas instead of words in order to describe the changes that takes place in a chemical reaction is known as chemical equation.  Reactants are the substances that are present in starting of the chemical reaction and it is entered in left side of the chemical equation.  Products are the substance that is obtained from the reactants as a final outcome of the chemical reaction and it is entered in right side of the chemical equation.  In order to write a chemical equation four conventions are used and they are,

• Correct formulas of the reactants are written in left side of chemical equation.
• Correct formulas of products are written in right side of chemical equation.
• An arrow is placed between reactants and products which point towards the products.
• If two or more substances are present in reactant and product, plus sign is used to separate them.

Balanced chemical equation is the one that has equal number of atoms of each element that is involved in the chemical reaction on both sides of the chemical equation.  An unbalanced chemical equation can be balanced by adding coefficients to the equation.  It is a number that is placed in left side of the chemical formula so that it changes the amount only and not the identity.

Answer to Problem 6.49EP

The balanced chemical equation is $2NaBr+C{l}_2\stackrel{}{\to }2NaCl+B{r}_2$.

Explanation of Solution

Given chemical equation is $NaBr+C{l}_2\stackrel{}{\to }NaCl+B{r}_2$.  Looking into the equation, the element that is occurring only once on both sides and the compound that has greater number of atoms has to be started with.  Starting with balancing chlorine atom,.

Balancing $Cl$ atoms:  There are two $Cl$ atoms on left side and one $Cl$ atom on the right side of the chemical equation.  Placing the coefficient 2 in front of $NaCl$ in the right side balances the $Cl$ atom on both sides.  This leaves $Na$ atoms to become unbalanced.

$NaBr+C{l}_2\stackrel{}{\to }2NaCl+B{r}_2$

Balancing $Na$ atoms:  There are one $Na$ atom on left side and two $Na$ atoms on the right side of the chemical equation.  Placing the coefficient 2 in front of $NaBr$ in the left side balances the $Na$ atom on both sides.  This leaves all the atoms on both sides to be balanced.

$2NaBr+C{l}_2\stackrel{}{\to }2NaCl+B{r}_2$

The number of atoms of each element on both sides have to be checked and it can be given as shown below,

$\begin{array}{l}\underset{\_}{AtomLeftsideRightside}\\ Na2x1=22x1=2\\ Br2x1=21x2=2\\ \underset{\_}{Cl1x2=22x1=2}\end{array}$

As there are same number of atoms of each element on both sides of the equation, it is said to be a balanced chemical equation.  The balanced chemical equation can be given as,

$2NaBr+C{l}_2\stackrel{}{\to }2NaCl+B{r}_2$

Conclusion

Given chemical equation is balanced.

(d)

Interpretation Introduction

Interpretation:

The chemical equation $ZnS+O_2\stackrel{}{\to }ZnO+S{O}_2$ has to be balanced.

Concept Introduction:

Statement that uses chemical symbols and formulas instead of words in order to describe the changes that takes place in a chemical reaction is known as chemical equation.  Reactants are the substances that are present in starting of the chemical reaction and it is entered in left side of the chemical equation.  Products are the substance that is obtained from the reactants as a final outcome of the chemical reaction and it is entered in right side of the chemical equation.  In order to write a chemical equation four conventions are used and they are,

• Correct formulas of the reactants are written in left side of chemical equation.
• Correct formulas of products are written in right side of chemical equation.
• An arrow is placed between reactants and products which point towards the products.
• If two or more substances are present in reactant and product, plus sign is used to separate them.

Balanced chemical equation is the one that has equal number of atoms of each element that is involved in the chemical reaction on both sides of the chemical equation.  An unbalanced chemical equation can be balanced by adding coefficients to the equation.  It is a number that is placed in left side of the chemical formula so that it changes the amount only and not the identity.

Answer to Problem 6.49EP

The balanced chemical equation is $2ZnS+3O_2\stackrel{}{\to }2ZnO+2S{O}_2$.

Explanation of Solution

Given chemical equation is $ZnS+O_2\stackrel{}{\to }ZnO+S{O}_2$.  Looking into the equation, the element that is occurring only once on both sides and the compound that has greater number of atoms has to be started with.  Starting with balancing oxygen atom.

Balancing $O$ atoms:  There are two $O$ atoms on left side and three $O$ atoms on the right side of the chemical equation.  Placing the coefficient 3 in front of $O_2$ in the left side, coefficient 2 in front of both $ZnO$ and $S{O}_2$ on right side, balances the $O$ atoms on both sides.  This leaves $Zn$ and $S$ atoms to become unbalanced.

$ZnS+3O_2\stackrel{}{\to }2ZnO+2S{O}_2$

Balancing $Zn$ atoms:  There are one $Zn$ atom on left side and two $Zn$ atoms on the right side of the chemical equation.  Placing the coefficient 2 in front of $ZnS$ in the left side balances the $Zn$ atom on both sides.  This leaves all the atoms on both sides to be balanced.

$2ZnS+3O_2\stackrel{}{\to }2ZnO+2S{O}_2$

The number of atoms of each element on both sides have to be checked and it can be given as shown below,

$\begin{array}{l}\underset{\_}{AtomLeftsideRightside}\\ Zn2x1=22x1=2\\ S2x1=21x2=2\\ \underset{\_}{O3x2=62+4=6}\end{array}$

As there are same number of atoms of each element on both sides of the equation, it is said to be a balanced chemical equation.  The balanced chemical equation can be given as,

$2ZnS+3O_2\stackrel{}{\to }2ZnO+2S{O}_2$

Conclusion

Given chemical equation is balanced.