CELL VOLTAGE
Introduction
Oxidation and reduction are two essential chemical reactions that require the
transfer of electrons between species. In oxidation, a material loses electrons,
whereas in reduction, it obtains electrons. These mechanisms are frequently
combined in chemical reactions to preserve charge neutrality.
What is Oxidation?
Oxidation is a chemical process in which an atom, molecule, or ion loses one or
more electrons. During oxidation, a material loses electrons to another species,
increasing its oxidation state.
For example, consider the reaction between hydrogen gas (H2) and oxygen gas
(O2) to form water (H2O):
What is Reduction?
Reduction is a chemical process in which an atom, molecule, or ion gains one or
more electrons, decreasing its oxidation state or oxidation number.
Reduction is a fundamental concept in chemistry that describes the acquisition of
one or more electrons by an atom, molecule, or ion. Here's an illustration of a
reduction reaction:
In this process, copper(II) oxide (CuO) is reduced to copper (Cu) by acquiring two
electrons. The hydrogen gas (H2) is the reducing agent, donating electrons to the
copper(II) oxide.
,What is REDOX?
REDOX is a chemical process in which electrons are transferred from one species
to another, causing a change in the oxidation state of the species involved. In a
REDOX reaction, one molecule oxidizes (loses one or more electrons), while
another species reduces (gains one or more electrons). Oxidation is the loss of
electrons, whereas reduction is the gain of electrons.
Many biological and commercial processes rely on REDOX reactions, such as
cellular respiration, photosynthesis, and battery-based power generation. REDOX
reactions play an important part in many facets of our existence. REDOX stands for
reduction and oxidation. In this reaction, electrons are transported from the
reducing agent to the oxidizing agent. An oxidant is reduced, whereas a reductant is
oxidized.
Redox reactions include electrochemical processes such as those in batteries and
fuel cells, metal corrosion, burning of fuels, and photosynthesis.
For example, if magnesium is introduced to a solution of copper sulphate, the
magnesium metal will oxidize while the copper ions will decrease.
Other examples include:
Cu(s) → Cu 2+ (aq) + 2e- /oxidation reaction
2Ag+ (aq) +-2e → 2Ag (s) /reduction reaction
Cu (s) +2Ag+ (aq) → Cu2+ (aq) + 2Ag (s) /redox reaction
A displacement reaction can also be referred to as a single displacement or
substitution reaction. This occurs when a more reactive component drives out a
less reactive element from its complex.
A displacement reaction is generally represented as follows:
,In some displacement reactions, one species undergoes oxidation by losing
electrons, while the other species undergoes reduction by gaining electrons.
Differences between a REDOX and a displacement reaction:
Displacement reactions may not always involve redox processes, unlike redox
reactions which by definition include both oxidation and reduction.
KEY DIFFERENCES
• Electron transfer is a key feature of redox reactions, which involve the
movement of electrons between molecules. In contrast, displacement
reactions entail the swapping of elements among compounds.
• Oxidation states are pivotal in redox reactions, as they undergo changes.
Conversely, in displacement reactions, the oxidation states of the atoms
involved might remain unaltered or may change. This distinction is crucial in
understanding the nature of these chemical processes.
• Reactivity is a key factor in displacement reactions, where the more reactive
element will displace a less reactive one from its compound. This process is
governed by the reactivity series of the elements, determining which element
can replace another in a chemical compound.
BALANCING HALF-REACTIONS AND OVERALL CELL REACTIONS
, In an electrochemical cell, the anode, which is the negative electrode, is where
oxidation takes place and electrons are released. Conversely, at the cathode, the
positive electrode, reduction happens as electrons are acquired.
Two half-cells are linked by a salt bridge or a permeable membrane, which permits
the flow of ions while maintaining the separation of the electrolyte solutions. The
total cell reaction represents the combined effect of the two half-reactions taking
place at each electrode.
Metal- Metal Half equation
When two half-cells are connected, they can be linked by a salt bridge or an open
membrane. This connection allows ions to flow between the two half-cells while
keeping their respective electrolyte solutions separate. The purpose of this setup is
to facilitate the movement of ions necessary for the electrochemical reactions to
occur.
The balanced overall redox equation is: 2Zn(s) + 2Cu2+(aq) → 2Zn2+(aq) + 2Cu(s)
Introduction
Oxidation and reduction are two essential chemical reactions that require the
transfer of electrons between species. In oxidation, a material loses electrons,
whereas in reduction, it obtains electrons. These mechanisms are frequently
combined in chemical reactions to preserve charge neutrality.
What is Oxidation?
Oxidation is a chemical process in which an atom, molecule, or ion loses one or
more electrons. During oxidation, a material loses electrons to another species,
increasing its oxidation state.
For example, consider the reaction between hydrogen gas (H2) and oxygen gas
(O2) to form water (H2O):
What is Reduction?
Reduction is a chemical process in which an atom, molecule, or ion gains one or
more electrons, decreasing its oxidation state or oxidation number.
Reduction is a fundamental concept in chemistry that describes the acquisition of
one or more electrons by an atom, molecule, or ion. Here's an illustration of a
reduction reaction:
In this process, copper(II) oxide (CuO) is reduced to copper (Cu) by acquiring two
electrons. The hydrogen gas (H2) is the reducing agent, donating electrons to the
copper(II) oxide.
,What is REDOX?
REDOX is a chemical process in which electrons are transferred from one species
to another, causing a change in the oxidation state of the species involved. In a
REDOX reaction, one molecule oxidizes (loses one or more electrons), while
another species reduces (gains one or more electrons). Oxidation is the loss of
electrons, whereas reduction is the gain of electrons.
Many biological and commercial processes rely on REDOX reactions, such as
cellular respiration, photosynthesis, and battery-based power generation. REDOX
reactions play an important part in many facets of our existence. REDOX stands for
reduction and oxidation. In this reaction, electrons are transported from the
reducing agent to the oxidizing agent. An oxidant is reduced, whereas a reductant is
oxidized.
Redox reactions include electrochemical processes such as those in batteries and
fuel cells, metal corrosion, burning of fuels, and photosynthesis.
For example, if magnesium is introduced to a solution of copper sulphate, the
magnesium metal will oxidize while the copper ions will decrease.
Other examples include:
Cu(s) → Cu 2+ (aq) + 2e- /oxidation reaction
2Ag+ (aq) +-2e → 2Ag (s) /reduction reaction
Cu (s) +2Ag+ (aq) → Cu2+ (aq) + 2Ag (s) /redox reaction
A displacement reaction can also be referred to as a single displacement or
substitution reaction. This occurs when a more reactive component drives out a
less reactive element from its complex.
A displacement reaction is generally represented as follows:
,In some displacement reactions, one species undergoes oxidation by losing
electrons, while the other species undergoes reduction by gaining electrons.
Differences between a REDOX and a displacement reaction:
Displacement reactions may not always involve redox processes, unlike redox
reactions which by definition include both oxidation and reduction.
KEY DIFFERENCES
• Electron transfer is a key feature of redox reactions, which involve the
movement of electrons between molecules. In contrast, displacement
reactions entail the swapping of elements among compounds.
• Oxidation states are pivotal in redox reactions, as they undergo changes.
Conversely, in displacement reactions, the oxidation states of the atoms
involved might remain unaltered or may change. This distinction is crucial in
understanding the nature of these chemical processes.
• Reactivity is a key factor in displacement reactions, where the more reactive
element will displace a less reactive one from its compound. This process is
governed by the reactivity series of the elements, determining which element
can replace another in a chemical compound.
BALANCING HALF-REACTIONS AND OVERALL CELL REACTIONS
, In an electrochemical cell, the anode, which is the negative electrode, is where
oxidation takes place and electrons are released. Conversely, at the cathode, the
positive electrode, reduction happens as electrons are acquired.
Two half-cells are linked by a salt bridge or a permeable membrane, which permits
the flow of ions while maintaining the separation of the electrolyte solutions. The
total cell reaction represents the combined effect of the two half-reactions taking
place at each electrode.
Metal- Metal Half equation
When two half-cells are connected, they can be linked by a salt bridge or an open
membrane. This connection allows ions to flow between the two half-cells while
keeping their respective electrolyte solutions separate. The purpose of this setup is
to facilitate the movement of ions necessary for the electrochemical reactions to
occur.
The balanced overall redox equation is: 2Zn(s) + 2Cu2+(aq) → 2Zn2+(aq) + 2Cu(s)
