Chapter 19, Problem 1P

(a)

Summary Introduction

To determine: The electron donor in reaction:

(1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$,

(2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$,

(3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$.

Introduction:

Oxidation-reduction reactions are those reactions which involve the change in the oxidation state of participating atoms. These reactions involve the transfer of electrons. The chemical compound from which electron is removed is termed as oxidized and in which electron is added is said to be reduced.

Explanation of Solution

Explanation:

The electron donor is the chemical species in a chemical reaction which donates the electron. Since they donate electron and themselves become oxidized they are also referred to as reducing agents.

In reaction (1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$, NADH has donated electron and itself it became oxidized. So in this reaction, NADH is the electron donor.

In reaction (2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$, E-FMNH₂ has donated electron and became oxidized. So, in this reaction, E-FMNH₂ is the electron donor.

In reaction (3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$, Fe²⁺ as donated electron and became oxidized to Fe³⁺. So, in this reaction, Fe²⁺ is the electron donor.

(b)

Summary Introduction

To determine: The electron acceptor in reaction:

(1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$,

(2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$,

(3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$.

Introduction:

Oxidation-reduction reactions are those reactions which involve the change in the oxidation state of participating atoms. These reactions involve the transfer of electrons. The chemical compound from which electron is removed is termed as oxidized and in which electron is added is said to be reduced.

Explanation of Solution

Explanation:

The electron acceptor is the chemical species which accepts electron from the donor species and becomes oxidized. Since electron acceptor accepts electron they are also known as oxidizing agent.

In reaction (1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$, E-FMN is the electron acceptor as it is accepting electron from NADH.

In reaction (2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$, Fe³⁺ is the electron acceptor as it is accepting electron from E-FMNH₂ and it is getting reduced to Fe²⁺.

In reaction (3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$, Q is the electron acceptor as it is accepting electrons from Fe²⁺and is getting reduced to QH₂.

(c)

Summary Introduction

To determine: Conjugate pair in reaction:

(1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$,

(2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$,

(3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$.

Introduction:

Oxidation-reduction reactions are those reactions which involve the change in the oxidation state of participating atoms. These reactions involve the transfer of electrons. The chemical compound from which electron is removed is termed as oxidized and in which electron is added is said to be reduced.

Explanation of Solution

Explanation:

Conjugate pair is the pair of two chemical species in which one is the electron donor and another is the electron acceptor species.

In reaction (1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$, there are two conjugate pairs NADH/ NAD⁺and E-FMNH₂/ E-FMN.

In reaction (2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$, the conjugate pairs are Fe³⁺/ Fe²⁺ and E-FMNH₂/ E-FMN.

In reaction (3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$, the conjugate pair are Fe³⁺/ Fe²⁺ and Q/QH₂.

(d)

Summary Introduction

To determine: The reducing agent in reaction

(1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$,

(2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$,

(3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$.

Introduction:

Oxidation-reduction reactions are those reactions which involve the change in the oxidation state of participating atoms. These reactions involve the transfer of electrons. The chemical compound from which electron is removed is termed as oxidized and in which electron is added is said to be reduced.

Explanation of Solution

Explanation:

The reducing agents are those chemical species which donate electron and they become oxidizing, thereby reducing it.

In reaction (1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$, NADH is the reducing agent as it is reducing E-FMN to E-FMNH₂.

In reaction (2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$, E-FMNH₂ is the reducing agent as it is reducing Fe³⁺to Fe²⁺.

In reaction (3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$, Fe²⁺ is the reducing agent as it is reducing Q toQH₂.

(e)

Summary Introduction

To determine: The oxidizing agent in reaction:

(1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$,

(2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$,

(3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$.

Introduction:

Oxidation-reduction reactions are those reactions which involve the change in the oxidation state of participating atoms. These reactions involve the transfer of electrons. The chemical compound from which electron is removed is termed as oxidized and in which electron is added is said to be reduced.

Explanation of Solution

Explanation:

The oxidizing agents are those chemical species which accepts electron, thereby themselves becoming reduced and oxidizing the other species.

In reaction (1) $\text{NADH}+{\text{H}}^{\text{+}}+\text{E-FMN}\to {\text{NAD}}^{\text{+}}+{\text{E-FMNH}}_{\text{2}}$, E-FMN is the oxidizing agent, as it is oxidizing, NADH to NAD⁺.

In reaction (2) ${\text{E-FMNH}}_{\text{2}}+{\text{2Fe}}^{\text{3+}}\to \text{E-FMN}+{\text{2Fe}}^{\text{2+}}+{\text{H}}^{\text{+}}$, Fe³⁺ is the oxidizing agent as it is oxidizing E-FMNH₂ to E-FMN.

In reaction (3) ${\text{2Fe}}^{\text{2+}}+{\text{2H}}^{\text{+}}+\text{Q}\to {\text{2Fe}}^{\text{3+}}+{\text{QH}}_{\text{2}}$, Q is the oxidizing agent as it is oxidizing Fe²⁺to Fe³⁺.