Identifying the Concepts of Reduction and Oxidation (Redox) Reactions

Definition of Reduction Reaction – Reduction and reducing agent are two words that are
related to one another.
These two words are often found in chemistry lessons at the junior high
school (SMP) and high school (SMA) levels.

For ordinary people, the word is rarely heard and the use of the word is also very rare, even though the
two words have the meaning of something that happens in everyday life.
It’s just that most
people don’t know about it.

So, what is meant by reduction, along with reduction reactions, and examples of reduction reactions?
Check out the following explanation.

Definition of Redox Reactions

What is a redox reaction? Redox reaction stands for reduction and oxidation reactions that
take place in electrochemical processes.
In general, redox is a term that describes changes in
the oxidation number (oxidation state) of atoms in a chemical reaction.
This can be a simple
redox process, such as the oxidation of carbon to give carbon dioxide, or the reduction of carbon by
hydrogen to give methane (CH
4 ), or it can be a complex process such as the
oxidation of sugar in the human body through a complicated sequence of electron transfers.

The term redox comes from two concepts, namely reduction and
oxidation . The concept can be explained easily as
follows.

  • Oxidation describes the loss of electrons by a molecule, atom, or ion.
  • Reduction describes the gain of electrons by a molecule, atom, or ion.

Although quite appropriate for use in various purposes, the above explanation is not exactly correct.
Oxidation and reduction precisely refer to changes in oxidation number because
actual transfer of electrons will not always occur.
Therefore, oxidation is better defined
as
an increase in oxidation number , while reduction as a decrease in
oxidation number .

In practice, the transfer of electrons will always change the oxidation number, but there are many
reactions that are classified as “redox”, even though there is no transfer of electrons in those reactions
(eg those involving covalent bonds).
Non-redox reactions that do not involve a change in formal
charge
are known as metathesis reactions.

The following is the meaning of the two terms.

1. Definition of Reduction

Reduction is an electron capture reaction or a reduction in oxidation number reaction, while a reducing
agent is a substance that carries out the process of reducing other substances.
Reduction is a
reaction event that experiences a decrease in oxidation number and an increase in electrons.
Based on this explanation, reduction can be said to be a reaction when a substance loses
oxygen.

According to the Big Indonesian Dictionary
(KBBI),
reduction is a reduction or reduction (price and so on).
Example of use: the store provides a 20% reduction ahead of Eid.

a. Definition
of Data Reduction

Data reduction is a form of analysis with the aim of sharpening, directing, classifying, organizing data, and
removing unnecessary things in such a way, so that final conclusions can be drawn and verified.

According to Sugiyono, data reduction is summarizing, choosing the main things, focusing on important things that
are appropriate to the research topic, looking for themes and patterns, which in turn provide a clearer picture
and make it easier to carry out further data collection.

b. Definition of
Reduction Reaction

A reduction reaction is a reaction when an atom experiences a decrease in its oxidation number.
It can be said that a reduction reaction is a reaction when a substance loses oxygen.
Examples of redox reactions in everyday life are rusting, combustion, decay, photosynthesis and
metabolism.

Many things can be done with reduction events, for example dissolving nitric acid for raw materials for the
chemical industry or agricultural fertilizers, testing for sulfate content in salt, avoiding seawater
contamination in the process of cyanidation of gold minerals, and the chemical element arsenic.

2. Definition of Oxidation

Oxidation is a term that you need to understand, especially when studying chemistry. KBBI
states that oxidation is the combination of a substance with oxygen.
Oxidation itself is the
loss of electrons by a molecule, atom or ion.
This is different from reduction which is the
gain of electrons by a molecule, atom, or ion.

Oxidation state in chemistry is an indicator of the degree of oxidation of an atom in a chemical compound.
The oxidation state includes an integer consisting of a positive, negative or zero value.
For pure compound elements themselves the oxidation state is zero.

—–

Oxidation and reduction of course refer to changes in oxidation number, because the actual transfer of
electrons will not always occur, so oxidation is better defined as an increase in oxidation number and
reduction as a decrease in oxidation number.
Such reactions involve the transfer of
electrons.

If based on the transfer or transfer of electrons, the reduction reaction is a point electron capture
reaction Meanwhile, the oxidation reaction is a reaction of releasing electrons.
In practice,
the transfer of electrons will always change oxidation number, but there are many reactions that need to be
classified as redox, even though there is no transfer of electrons in the reaction, such as something
involving covalent bonds.
A non-redox reaction that does not involve a change in formal
charge is known as a metathesis reaction.

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Redox concept

So, to find out more clearly about redox reactions, the following has presented a discussion of the concept
of redox.
Chemical reactions involving redox or reduction-oxide reactions are more frequently
used in titrimetric analysis than acid-base reactions, complex formation or precipitation.
The
ions of various elements exist in different oxidation states, which is why there are so many possible redox
or oxidation-reduction reactions.

The development of the redox reaction concept resulted in three concepts, namely classical theory, modern
theory, and the concept of numbers.
Then, what are the differences between the three?
Come on, pay attention to the full discussion below.

1. Classical Theory

The classical theory says that oxidation is a process of capturing oxygen and losing hydrogen.
However, on the other hand reduction is a process of losing oxygen and capturing hydrogen.

2. Modern Theory

The concept of redox has developed through various experiments, giving rise to the modern theory.
Where, this modern theory says that oxidation is a process that results in the loss of one or more
electrons from a substance.
Substances that undergo oxidation will turn out to be more
positive.

Meanwhile, reduction itself is a process that results in the acquisition of one or more electrons by a
substance.
Where, substances that undergo this reduction process will become more negative.
From these two theories and reduction which is not only seen from the capture of oxygen and
hydrogen but as a process of transferring electrons from one substance to another.

3. Concept of Oxidation Numbers

The concept of a redox reaction involving the transfer of electrons can only occur in ionic compounds.
Meanwhile, in covalent compounds it is not. For this reason, a third redox concept
emerged, which is based on changes in oxidation numbers or also called oxidation states.

Oxidation number is the positive and negative charges on an atom. The positive oxidation
number element itself is generally an atom of a metal element, for example Na, Fe, Mg, Ca, and other metal
elements.
Meanwhile, elements with negative oxidation numbers are generally atoms of
non-metallic elements, for example O, Cl, F, and other non-metallic elements.

According to the concept of change in oxidation number, states that a reduction reaction is a reaction in
which the oxidation number decreases.
Meanwhile, the oxidation reaction itself is a reaction
that experiences an increase in oxidation number.

Where, there are 8 (eight) rules in determining the oxidation number of an atom that you must know, including the
following:

1. The concept of the oxidation number of free elements in the form of atoms and molecules, namely
O

Atomic free samples.
C, Ca, Cu, Na, Fe, Al, Ne = 0
Free examples are
molecules.

For example H2, O2, CI2, P4, S8, = 0.

2. The concept of the oxidation number of monoatomic and polyatomic ions according to the type of ionic
charge

For example:
The oxidation numbers of monoatomic ions Na+, Mg2+, and AI3+ are +1, +2, and +3,
respectively.

The oxidation numbers of polyatomic ions NH4+, SO42-, and PO43- are +1, -2,
and -3, respectively.

3. The concept of the oxidation number of elements in metal groups IA, IIA, and IIIA according to
group

An example of the oxidation number of Na in a NaCl compound is +1
Such as: IA = H, Li, Na, K, Rb, Cs, Fr
= +1.

An example of the oxidation number of Mg in the compound MgSO2 is
+2.

Such as: IIA = Be, Mg, Ca, Sr, Ba, Ra = +2.
An example of the oxidation
number of Al in the AI203 compound is +3.

Like IIIA = B, Al, Ga, In, Tl = +3.

4. The concept of oxidation numbers for more than one transition group or group B elements

Example:
Oxidation numbers of Cu = +1 and +2.
Au oxidation number = +1 and
+3.

Sn oxidation numbers = +3 and +4.

5. The concept of the total oxidation number of the elements that form ions = the total charge

For example: NH4+ = +1

6. The concept of the sum of the oxidation numbers of the elements that form compounds = 0

For example: H2O = 0

7. The concept of Hydrogen Oxidation Number (H) When Associated with Metals = -1 But when H is related to
non-metals = +1

For example: The oxidation number of H in AIH3 = -1

8. Concept of Oxygen Number (O) in Peroxide Compounds = -1 and Oxidation Number of O in Non Peroxide
Compounds = -2

For example: The oxidation number of O in the compound BaO2 = -1.

How to Determine Reduction and Oxidation (Redox) Reactions Based on the Concept of Increasing and
Decreasing Oxidation Numbers

In reduction and oxidation (redox) reactions, there are several elements that act as reducing agents and
oxidizing agents.
Where, the substance that is being oxidized is called a reducing agent, while
the substance that is being reduced is called an oxidizing agent.

Try to look at the following example:
Reaction Mg(s) + 2HCl —–> MgCl2(aq) +
H2(g)

Because Mg is a free element, so the oxidation number of Mg = 0. Then, the
oxidation number of H in the 2HCl compound is +1 because H elements are related to other elements and H
is a group of IA.
Furthermore, because H = +1, it means that Cl = -1 so that the total
oxidation number of 2HCl = 0.

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On the right-hand side, the oxidation number of Mg in the compound MgCl is +2 because Mg is bonded and is a
group IIA element.
This is because Cl has an index of 2, so the oxidation number of Cl = -1 so
that the total oxidation number of MgCl2 = 0. In addition, because H2 is a free element, the oxidation
number has a value of 0. Where, the element Mg experiences an increase in oxidation number from 0 to +2 So
it will undergo an oxidation reaction.

So that the element Mg can be said to be a reducing agent. Meanwhile, element H will
experience a decrease in its oxidation number from +1 to 0, so it will undergo a reduction reaction.
Therefore, HCl is called an oxidizing agent.

Examples of Redox Reactions

One example of a redox reaction is between hydrogen and fluorine:
H2 + F2 a 2 HF

You can write all these reactions as 2 (two) half reactions:
Oxidation reaction: H2 a 2H+ +
2e-

Reduction reaction: F2 + 2e- a 2F-

Analyzing each half reaction will make the whole chemical process appear more clearly. That is
because there is no change in total charge during a redox reaction, the total excess electrons in an
oxidation reaction must equal the number consumed in a reduction reaction.

Elements even in this molecular form often have an oxidation number of zero. In the above
reaction hydrogen is oxidized from 0 to +1, while fluorine is reduced from 0 to -1.
When
oxidation and reduction reactions are combined the electrons involved reduce each other:

H2 a 2H+ + 2e-
F2 + 2e- à 2F-
______________________
H2 + F2 a 2H+ +
2F-

And the ions combine to form hydrogen fluoride:
H2 + F2 a 2H+ + 2F- a 2
HF

Example of Reduction Reaction

Examples of reduction reactions can occur when chlorine gas Cl2 turns into chlorine ions Cl-, Iron Cation III
(Fe3+) changes to Iron II (Fe2+) or iron (Fe), or when copper Cation II (Cu2+) changes to copper metal Cu.

An example of a reduction reaction is as follows.

The two reactions above are events of the release of oxygen by a substance.

The two reactions above are events of binding electrons by a substance.

The oxidation number of S drops from +6 to +4.

Difference between
Reduction and Oxidation

The notions of reduction and reducer are interrelated. If you look at the context of the word,
the word reduction is a word that contains the meaning of an event.
While the reducer is an
object that functions to carry out the event.

In reduction there is an event of gaining electrons, or decreasing the oxidation number of an atom,
molecule, or ion.
While reducing agents are substances that carry out the process of reducing
other substances.

Reduction occurs due to the presence of a reducing agent, which is a material in the form of molecules,
atoms, or ions, which reduces other molecules, atoms, or ions.
When the process occurs, the
reducing agent actually undergoes the opposite process, namely oxidation.

Oxidation is the loss of electrons or the addition (increase) of oxidation number. Reduction
has events that are always stimulants with oxidation events, meaning that each reduction event always causes
an oxidation reaction.
The words reduction and reducing agent in a chemical reaction always
meet with pairs of words oxidizing and oxidizing.

Oxidizing and Reducing

Compounds that have the ability to oxidize other compounds are said to be
oxidative and are known as oxidizing agents or oxidizing
agents
. The oxidizing agent removes electrons from other compounds,
thereby reducing itself.
Because it “accepts” electrons, it is also called an electron
acceptor.
Oxidizing agents are usually compounds that have elements with a high oxidation
number (such as H, MnO, CrO
3 , Cr, OsO 4 ) or
compounds that are very electronegative, so they can gain one or two more electrons by oxidizing a compounds
(eg oxygen, fluorine, chlorine, and bromine).

Compounds that have the ability to reduce other compounds are said to be
reductive and are known as reducing agents or reducing
agents
. The reducing agent gives up its electrons to another compound, so
that it itself is oxidized.
Because it “donates” electrons, it is also known as an electron
donor.
Compounds that are reducing agents vary widely.

Metal elements such as Li, Na, Mg, Fe, Zn, and Al can be used as reducing agents. These metals
will
give their electrons easily. Another type of reducing agent is
the hydride transfer reagents , for example NaBH 4 and LiAlH
4 ), these reagents are used extensively in organic chemistry, especially in the
reduction of carbonyl compounds to alcohols.

Another useful reduction method involves gaseous hydrogen (H 2 ) over a palladium, platinum, or
nickel catalyst. This
catalytic reduction is primarily used in the reduction of
carbon-carbon double or triple bonds.
An easy way to look at redox processes is, the
reducing agent transfers its electrons to the oxidizing agent.
So in a reaction, the
reducing agent loses electrons and is oxidized, and the oxidizing agent gains electrons and is reduced.
The oxidizing and reducing pairs involved in a reaction are known as
redox pairs .

So, that’s an explanatory article about reduction along with the process and examples of reduction
reactions.
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