The Concept Of Oxidation & Reduction

Oxidation can be defined as loss of electron or gain of oxygen or removal of hydrogen while the term reduction indicates the gain of electron or gain of hydrogen or removal of oxygen. According to classical concept, oxidation is an addition of oxygen or electronegative radical/element removal of hydrogen or electropositive radical/element. According to classical concept, the reduction is an addition of hydrogen or electropositive radical/element removal of oxygen or electronegative radical/element.

Summary

Things to Remember

Oxidation and reduction can be simply understood by the term LEOGER which means Loss of Electron Oxidation Gain of Electron Reduction.
The chemical substance/species (atoms or compounds) that accepts electron & decrease its own oxidation number is known as oxidizing agent or oxidant.
The chemical substance/species (atoms or compounds) which can reduce other (increase negative charge) & itself gets oxidized (decrease in negative charge). Such substances are called reducing agent or reductant.

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Subjective Questions

Q1:

Explain the health teaching to be given to the mother in antenatal visit ?

Type: Long Difficulty: Easy

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Answer:  
<ol>
<li>Diet</li>
</ol>
 
The pregnant woman's food requirement increases during pregnancy and she needs to eat more protein, minerals, and vitamins. She has to keep herself healthy and also to supply materials that will help develop her body. If she eats right kind of food during pregnancy, she and the growing fetus will be healthy.
 
Importance of diet in pregnancy
<ul>
<li>The maintenance of maternal health</li>
<li>The need of growing fetus</li>
<li>The strength and vitality required during labour</li>
<li>Preparation of successful lactation</li>
<li>Prevent complication during the pre-natal , natal and postnatal period</li>
</ul>
During pregnancy there is increased calorie requirement due to increased growth of the maternal tissue, fetus, placenta and increased basal metabolic rate. The woman should encourage to take micronutrient like: vitamin A , iodine , iron, folic acid, calcium
Macronutrient: protein carbohydrates
 
 
<ol start="2">
<li>Hygiene</li>
</ol>
There are more sweating and vaginal discharge during pregnancy because of hormonal activities so she should need to take frequent baths and keeps the body clean. A daily bath is needed in hot weather. Dental, breast care is needed.
 
<ol start="3">
<li>Comfortable clothing and shoes</li>
</ol>
The pregnant woman should wear loose and comfortable clothes such as loose blouse or cholo. Her clothes should not be tight. brassieres should support and lift the breast well. Pregnant woman should avoid high heeled shoes. She should wear flat shoes to maintain Centre of balance.
 
<ol start="4">
<li>Exercise</li>
</ol>
Most Nepali women get enough exercise looking after their hole and family. They also work in the field so not need extra exercise. If the woman is on sedentary life style, she should have exercise. The family members must understand that excessive hard work and carrying heavy loads may result in abortion or premature labour.
 
<ol start="5">
<li>Antenatal visit</li>
</ol>
The woman should persuade to attend four antenatal checks up positively on the schedule date of visit. She should attend ANC clinic as she is diagnosed as pregnancy. Then if the woman is well and everything is normal , she should come to clinic for minimum of four visits as following schedule :
<ul>
<li>1st visit during 3rd month</li>
<li>2nd visit during 6th month</li>
<li>3rd visit during 8th month</li>
<li>4th visit during 9th month</li>
</ul>
 
But if she is suffering from any disorders or diseases, she should be seen weekly or as needed or admitted to hospital depending on the severity.
 
<ol start="6">
<li>Immunization</li>
</ol>
 
Tetanus is a common infectious disease in Nepal. Neonatal death due to tetanus is quite high so the pregnant woman should be immunized against tetanus. TT immunization protects, both mother and neonate. The dose is 0.5 ml intramuscularly in the upper arm. Usually, 2 or 3 doses of TT are given during pregnancy.
The 1st dose is given at 24-30 weeks of pregnancy and then next dose is given after 4 weeks so a woman should advice when next dose is due and record TT vaccine on mother card.
Tetanus toxoid schedule for pregnant woman and or other woman as following
<ul>
<li>At 1st contact with woman of childbearing age or at 1st ANC visit, as early as possible : TT1</li>
<li>At least 4 weeks after TT1 : TT2</li>
<li>At least 6 months after TT2 : TT3</li>
<li>At least one year after TT3 : TT4</li>
<li>At least one year after TT4 : TT5</li>
</ul>
 
<ol start="7">
<li>Safe sex and sexual relation</li>
</ol>
 
Coitus should be avoided during the first trimester preferable during the time of missed periods and also during the last 6 weeks prior to EDD for introduction of infection and premature labour in the last period. As the pregnancy progress changes in sexual position may be needed to accommodates the woman's enlarged abdomen or satisfy both partners sexual needs. Safe sex should be practice to reduce the risk of HIV and other sexually transmitted infection.
 
 
<ol start="8">
<li>Smoking and alcohol</li>
</ol>
Smoking is injuries to health and pregnant woman must stop smoking because smoking causes low birth weight baby, premature labour etc alcohol drinking must be stopped before and during pregnancy. Daily drinking of 30 ml or more ethanol contain drink cause fetal alcohol syndrome which occur in one third cases with :
<ul>
<li>CNS dysfunction</li>
<li>Growth retardation in weight and length</li>
<li>Higher incidence of mild trimester abortion</li>
<li>Increased perinatal mortality and morbidity</li>
<li>Characteristics facial abnormalities, short palpebral fissure , short nose, hypoplastic maxilla</li>
</ul>
So pregnant woman and woman planning for pregnancy should counsel to quit smoking and alcohol drinking.
 
<ol start="9">
<li>Rest and sleep</li>
</ol>
The woman may continue her usual activities throughout pregnancy. However hard and strenuous work should e avoided especially in the first trimester and the last 6 weeks of pregnancy. Rest is important for the maintenance of good health. She should need adequate rest and relaxation average 10 hours (8hrs at night and 2hrs at noon) specially in last 6 weeks. Lateral position particularly on left is posture of choice. It is also unsafe to take long strenuous journey towards the end of pregnancy.
 
<ol start="10">
<li>Preparation for Delivery</li>
</ol>
A pregnant woman and her family should start getting ready for the baby from the 7-8 months of pregnancy.
<ol>
<li>Preparation of women for labour: The woman should be taught:</li>
</ol>
<ul>
<li>When and how to bear down in the 2nd stage of labour.</li>
<li>Diet during labour – mainly liquid.</li>
<li>Explain about labour – what to do and what not to do.</li>
<li>Delivery position.</li>
</ul>
<ol>
<li>After delivery</li>
</ol>
<ul>
<li>Brest care and breast feeding.</li>
<li>The way of handling baby</li>
<li>Baby bath-eye and cord care</li>
<li>Immunization of baby</li>
<li>Family planning</li>
<li>The needs of baby as warmth, feeding</li>
<li>Vulval toilet</li>
<li>Items needed for child birth</li>
<li>Baby wrapper (clean old cloth which should be soft).</li>
<li>Bathing soap</li>
<li>Mustard oil massaging the baby</li>
<li>Towel</li>
<li>Baby clothes, vest photo etc.</li>
<li>Napkin (made from old soft clothes)</li>
<li>Pillow filled with mustard seeds,</li>
<li>Blanket for baby</li>
</ul>
 
<ol>
<li>Items for mother</li>
</ol>
<ul>
<li>Petticoat and sari</li>
<li>Things for morning care,</li>
<li>Blouse</li>
<li>Sanitary pads, after a few weeks, she may use clean pieces of cloth.</li>
<li>Food stuff such as ghee, rice, dark molasses (chaku) meat etc.</li>
<li>Charcoal or wood should be stored for heating the room in the winter season.</li>
<li>If a mother is alone; an arrangement for a relative or any other person should be made who is willing to help her at home during early weeks of puerperium.</li>
</ul>
 
<ol>
<li>Items needed for conducting delivery in home:</li>
</ol>
There are essential items that are needed for delivery. The TBA and the midwife should be advised to keep the following things ready if the delivery is anticipated as home delivery:
<ul>
<li>Clean clothes</li>
<li>Bowls or dekchi</li>
<li>Soap/water</li>
<li>Brush to scrub hands</li>
<li>Sterile scissors or sterile razor</li>
<li>Two clamps, if available to clamp cord</li>
<li>Thread to tie cord</li>
<li>Mud pot to receive placenta</li>
<li>Cotton and gauze</li>
<li>Syringe, needle, and ergometrine.</li>
</ul>
 
<ol start="11">
<li>Drugs</li>
</ol>
 
<ul>
<li>A multidisciplinary approach is essential. Most localities will have a clearly defined drug dependency service with a readily accessible entry point.</li>
<li>Cocaine use in pregnancy is particularly serious and there is no substitute. It has been associated with spontaneous abortion, placental abruption, premature birth, low birth weight and sudden infant death syndrome. There is conflicting evidence regarding fetal abnormalities.</li>
<li>Opiate use is associated with increased incidence of intrauterine growth restriction and preterm delivery. This contributes to an increased rate of low birth weight and perinatal mortality. Maintenance treatment with an opiate substitute improves outcomes.</li>
<li>Women addicted to heroin who wish to become pregnant should be urged to enter a detoxification programme before conception and, if not, then at least be stabilised on methadone. Buprenorphine is also used as a substitute with apparently similar outcomes in pregnancy.</li>
<li>HIV and hepatitis B screening is carried out in all pregnant women in the UK but is especially important in known IV drug users. Hepatitis C screening is also recommended in this group.</li>
<li>The use of cannabis may be harmful to the fetus and is also associated with smoking and should be discouraged.</li>
<li>Cochrane reviews have found no convincing evidence for psychosocial interventions</li>
</ul>

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The Concept Of Oxidation & Reduction

Oxidation & Reduction

Oxidation can be defined as loss of electron or gain of oxygen or removal of hydrogen. The term reduction indicates a gain of electron or gain of hydrogen or removal of oxygen. Oxidation and reduction can be simply understood by the term LEOGER which means Loss of Electron Oxidation Gain of Electron Reduction.

There are 2 concepts that define Oxidation and Reduction

Classical Concept of Oxidation and Reduction
Electronic Concept of Oxidation and Reduction

Classical Concept of Oxidation and Reduction

According to classical concept, oxidation is

The addition of oxygen or electronegative radical/element.
Removal of hydrogen or electropositive radical/element.

$${2MgO+O_2\longrightarrow2MgO} \space (addition\space of\space oxygen)$$

$${FeCl_2}+3/2Cl_2\longrightarrow{Fecl_2}\space (addition\space of\space electronegative\space element)$$

$${H_2S}+Cl_2\longrightarrow{HCl+S}\space (removal\space of\space hydrogen)$$

$${Hg_2Cl_2\longrightarrow{HgCl_2}+Hg}\space (removal\space of\space elecetropositive\space element)$$

According to classical concept, reduction is

Addition of hydrogen or electropositive radical/element.
Removal of oxygen or electronegative radical/element.

$${NH_3}+{HCl}\longrightarrow{NH_4Cl}\space (addition\space of\space hydrogen)$$

$${2Na+H_2O}\longrightarrow2NaOH\space (addition\space of\space electropositive\space element)$$

$${2KClO_3\longrightarrow2KCl+3Cl_2}\space (removal\space of\space oxygen)$$

$${H_2S\longrightarrow{H_2}+S}\space (removal\space of\space electropositive\space element)$$

Electronic Concept of Oxidation & Reduction

According to Electronic Concept Oxidation is defined as

Loss of electron

a. Increase in positive charge.

b. Decrease in negative charge.

$$Mg\longrightarrow Mg^{++}+2e^{-} (loss\space of\space electron)$$

$$Fe^{++}\longrightarrow Fe^{+++}+e^{-} (increase\space in\space positive\space charge$$

$$2Cl^{-}\longrightarrow{Cl_2}+2e^{-} (decrease\space in\space negative\space charge)$$

According to Electronic Concept, reduction is defined as

Gain of electron

a. Decrease in positive charge

b. Increase in negative charge

$$O+2e^{-}\longrightarrow{O}^{--} (gain\space of \space electron)$$

$$Fe^{+++}+e^{-}\longrightarrow{Fe}^{++} (decrease\space in\space positive\space charge) $$

$$S+2e^{-}\longrightarrow{S}^{--} (increase\space in\space negative\space charge$$

Classification

Redox reaction
Disproportionation reaction

A. Redox reaction

According to modern concept, Oxidation means loss of electron and Reduction means a gain of an electron. If one chemical compound loses electron then other must be gaining it which shows oxidation and reduction occur in the same reaction. In a chemical reaction oxidation and reduction occurs simultaneously.

For e.g

$$Zn+H_2SO_4\longrightarrow{ZnSO_4}+H_2\uparrow$$

$$Zn+2H^{+}+SO_4^{--}\longrightarrow{Zn}^{++}+SO_4^{--}+H_2$$

Oxidation Half Reduction half

$$Zn\longrightarrow{Zn}^{++}+2e^{-} (loss\space of\space electron)$$

$$2H^{+}+2e^{-}\longrightarrow{H_2} (increase\space in\space negative\space charge)$$

Oxidation & Reduction In Terms Of Oxidation Number (O.N)

According to this concept, the increase in oxidation number means Oxidation (loss of the electron) whereas the decrease in oxidation number means Reduction (gain of electron).

$${Zn+H_2SO_4\longrightarrow{ZnSO_4}+H_2}$$

The O.N of Zn increased from 0 to 2 i.e Zn got oxidized.

The O.N of H₂ decreased from 2 to 0 i.e H₂ got reduced.

Oxidation Number & Valency

When all other atoms of a compound are removed, the remaining charge of an atom is known as oxidation number whereas the losing gaining or sharing capacity of an element during the chemical reaction is called valency.
Oxidation number can be a positive, negative or fractional number but except for inert gases i.e 0, the valency for all element is positive.
The oxidation number of the same element differs in the different compound like O.N of carbon in CO, CH₄, CH₂Cl₂ are +2, +4, 0 respectively whereas valency of an element is usually same like valency of carbon in CO, CH₄, CH₂Cl₂is 4. However, many elements show multiple valencies like valency of copper is 2 or 3.

Oxidizing Agent (Oxidant) & Reducing Agent (Reductant)

1. Oxidizing Agent (Oxidant)

a. Classical concept

The chemical substance/species (atoms or compounds) which can oxidize other (increase in positive charge) & itself gets reduced (decrease in positive charge). Such substances are called oxidizing agent or oxidant.

b. Electronic Concept

The chemical substance/species (atoms or compounds) that accepts electron & decrease its own oxidation number is known as oxidizing agent or oxidant.

For e.g. KMnO₄, K₂Cr₂O₇, concentrated HNO₃, concentrated H₂SO₄ etc.

2. Reducing Agent (Reductant)

a. Classical Concept

The chemical substance/species (atoms or compounds) which can reduce other (increase negative charge) & itself gets oxidized (decrease in negative charge). Such substances are called reducing agent or reductant.

b. Electronic Concept

The chemical substance/species (atoms or compound) that donate the electron and increase its own oxidation number is known as reducing agent or reductant.

For eg. Lithium aluminum hydride (LiAlH₄), all metals etc.

This concept can be described by the following reaction;

$${HNO_3+H_2S}\longrightarrow{NO}+{H_2S+S}$$

Here, HNO₃acts as an oxidizing agent cause it oxidized H₂S to S i.e it increased the oxidation number of sulphur from -2 to 0 whereas H₂S acts as a reducing agent cause it reduces HNO₃ to NO i.e it decreased the oxidation number from +5 to +2.

B. Disproportionate reaction

The redox reaction (i.e both oxidation and reduction happens in the same reaction) in which same chemical substance/species act as oxidizing as well as reducing agent. Such type of reaction is called disproportionate reaction.

This concept can be described by the following reaction

$$2NaOH+Cl_2\longrightarrow{NaCl}+NaClO+H_2O$$

In above reaction, Cl₂ gets reduced into NaCl i.e oxidation number of Cl₂ decreased from 0 to -1.

In the same reaction, Cl₂gets oxidized into NaClO i.e oxidation number of Cl₂increased from 0 to1.

In the above reaction, Cl₂ acts as both oxidizing & reducing agent. Hence, the reaction is a disproportionate reaction.

When the oxidation state of the element is intermediate i.e. intermediate between maximum and lowest then the element behaves as both oxidant and reductant.

Reference:

pulse, Tracy. Introduction to chemistry. u.s.a: flexbook, 2010.

Pathak, Sita Karki. The Text Book of Chemistry. Kathmandu: Vidhyarthi Pustak Bhandar, 2012.

Lesson

Oxidation and Reduction

Subject

Chemistry

Grade

Grade 11

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