Chapter 19, Problem 93GQ

(a)

Interpretation Introduction

Interpretation:

The balanced equation for the following reaction has to be determined.

1. (a) ${\text{Ag}}^{\text{+}}{\text{(aq) + C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CHO (aq) }\to {\text{ Ag(s) + C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CO}}_{\text{2}}\text{H (aq) (acid solution)}$

Concept introduction:

Steps for balancing reactions in ACIDIC solution:

1. 1. Balance all atoms except H and O in half reaction.
2. 2. Balance O atoms by adding water to the side missing O atoms.
3. 3. Balance the H atoms by adding ${\text{H}}^{\text{+}}$ to the side missing H atoms.
4. 4. Balance the charge by adding electrons to side with more total positive charge.
5. 5. Make the number of electrons the same in both half reactions by multiplication, while avoiding fractional number of electrons.

Steps for balancing reactions in BASIC solution:

1. 1. Balance all atoms except H and O in half reaction.
2. 2. Balance O atoms by adding water to the side missing O atoms.
3. 3. Balance the H atoms by adding ${\text{H}}^{\text{+}}$ to the side missing H atoms.
4. 4. Balance the charge by adding electrons to side with more total positive charge.
5. 5. Make the number of electrons the same in both half reactions by multiplication, while avoiding fractional number of electrons.
6. 6. Add the same number of ${\text{OH}}^{\text{-}}$ groups as there are ${\text{H}}^{\text{+}}$ present to both sides of the equation.

(b)

Interpretation Introduction

Interpretation:

The balanced equation for the following reaction has to be determined.

1. (b) ${\text{CH}}_3{\text{CH}}_2{\text{OH +Cr}}_2{\text{O}}_7\text{(aq)}\to {\text{ CH}}_3{\text{CO}}_2{\text{H(aq) + Cr}}^{3+}\text{ (acid solution)}$

Concept introduction:

Oxidation reaction:

The loss of electrons or the gain of oxigen atoms.And also increase their oxidation number.

$\text{Ag }\to {\text{ Ag}}^{\text{+}}{\text{+ e}}^{\text{-}}$

In the above reaction , Ag atom lose one electron and change their oxidation state 0 to 1.

Reduction reaction:

Gaining electrons or adding hydrogen atoms. And also decrease their oxidation number.

${\text{Fe}}^{\text{2+}}{\text{+2e}}^{\text{-}}\to \text{ Fe}$

In the above reaction ${\text{Fe}}^{\text{2+}}$ ion gaining 2 electrons and reduce their oxidation number +2 to 0.

Steps for balancing reactions in ACIDIC solution:

1. 6. Balance all atoms except H and O in half reaction.
2. 7. Balance O atoms by adding water to the side missing O atoms.
3. 8. Balance the H atoms by adding ${\text{H}}^{\text{+}}$ to the side missing H atoms.
4. 9. Balance the charge by adding electrons to side with more total positive charge.
5. 10. Make the number of electrons the same in both half reactions by multiplication, while avoiding fractional number of electrons.

Steps for balancing reactions in BASIC solution:

1. 7. Balance all atoms except H and O in half reaction.
2. 8. Balance O atoms by adding water to the side missing O atoms.
3. 9. Balance the H atoms by adding ${\text{H}}^{\text{+}}$ to the side missing H atoms.
4. 10. Balance the charge by adding electrons to side with more total positive charge.
5. 11. Make the number of electrons the same in both half reactions by multiplication, while avoiding fractional number of electrons.
6. 12. Add the same number of ${\text{OH}}^{\text{-}}$ groups as there are ${\text{H}}^{\text{+}}$ present to both sides of the equation.