Principles of Oxidation-Reduction Reactions - AP Chemistry
Card 1 of 154
In the following reaction, which compound is being oxidized?
In the following reaction, which compound is being oxidized?
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Hydrogen doesn't change. Cu2+ doesn't change (partnered with S2- then with SO42-). Sulfur goes from S2- and S6+(paired with 6 O2- with a 2– charge), showing an oxidation. Nitrogen goes from N5+ to N2+ meaning it was reduced.
Hydrogen doesn't change. Cu2+ doesn't change (partnered with S2- then with SO42-). Sulfur goes from S2- and S6+(paired with 6 O2- with a 2– charge), showing an oxidation. Nitrogen goes from N5+ to N2+ meaning it was reduced.
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Which of the following reactions involves the transfer of electrons?
Which of the following reactions involves the transfer of electrons?
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Redox reactions occur when one species is oxidized—loses electrons—and another is reduced—gains electrons. Thus, this is the only one of the given options that involves the transfer of electrons.
Redox reactions occur when one species is oxidized—loses electrons—and another is reduced—gains electrons. Thus, this is the only one of the given options that involves the transfer of electrons.
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Consider the following reaction:
What is the oxidizing agent, and what is the reducing agent?
Consider the following reaction:
What is the oxidizing agent, and what is the reducing agent?
Tap to reveal answer
Let's break down the reaction into two separate reactions:
and
We can see that copper loses electrons, while silver gains electrons. Recall that oxidation is loss and reduction is gain, with regard to electrons. Copper is oxidized and silver is reduced.
However, this question asks for the oxidizing agent and reducing agent. Recall that the oxidizing agent is reduced, while the reducing agent is oxidized. Since copper is oxidized, it is the reducing agent. Similarly, since silver is reduced, it is the oxidizing agent.
Let's break down the reaction into two separate reactions:
We can see that copper loses electrons, while silver gains electrons. Recall that oxidation is loss and reduction is gain, with regard to electrons. Copper is oxidized and silver is reduced.
However, this question asks for the oxidizing agent and reducing agent. Recall that the oxidizing agent is reduced, while the reducing agent is oxidized. Since copper is oxidized, it is the reducing agent. Similarly, since silver is reduced, it is the oxidizing agent.
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Which statement about this reaction is FALSE?
Which statement about this reaction is FALSE?
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In Cr2O3, Cr has a charge of +3. The chromium metal product is neutral, and therefore has a charge of 0. So, Cr is reduced from +3 to 0.
Remember, OIL RIG. Oxidation Is Loss (of electrons) and Reduction Is Gain (of electrons).
In Cr2O3, Cr has a charge of +3. The chromium metal product is neutral, and therefore has a charge of 0. So, Cr is reduced from +3 to 0.
Remember, OIL RIG. Oxidation Is Loss (of electrons) and Reduction Is Gain (of electrons).
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Methane combusts in the presence of oxygen according to the following reaction:
Which of the following statements is true concerning the reaction?
Methane combusts in the presence of oxygen according to the following reaction:
Which of the following statements is true concerning the reaction?
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By comparing the oxidation number of an atom as a reactant and its oxidation number as a product, we can determine if the atom has been oxidized or reduced. In increase in oxidation number indicates a loss of electrons, or oxidation. A decrease in oxidation number signals a gain of electrons, or reduction.
For electrochemistry, you should familiarize yourself with the traditional oxidation states of hydrogen 
, halogens 
, oxygen 
, and elemental atoms 
.
Carbon is initially in the form of methane, meaning that it is attached to four hydrogen atoms. The molecule is neutral, and each hydrogen has an oxidation number of 
. Carbon must have an initial oxidation state of 
in order to balance the molecular charge.
In the a product, carbon is attached to two oxygens, each with a charge of 
. Again, the molecule is neutral, so carbon must balance these charges. This means that carbon's final oxidation state is 
.
Since carbon went from an oxidation state of 
to 
, we can conclude that carbon has been oxidized in the reaction.
By comparing the oxidation number of an atom as a reactant and its oxidation number as a product, we can determine if the atom has been oxidized or reduced. In increase in oxidation number indicates a loss of electrons, or oxidation. A decrease in oxidation number signals a gain of electrons, or reduction.
For electrochemistry, you should familiarize yourself with the traditional oxidation states of hydrogen
Carbon is initially in the form of methane, meaning that it is attached to four hydrogen atoms. The molecule is neutral, and each hydrogen has an oxidation number of
In the a product, carbon is attached to two oxygens, each with a charge of
Since carbon went from an oxidation state of
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Consider the following reaction:
Which of the following statements is true?
Consider the following reaction:
Which of the following statements is true?
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For any oxidation-reduction reaction, the oxidized atom will lose electrons and the reduced atom will gain electrons. Zinc is originally in elemental form, so it has an initial oxidation state of zero. As a product, it has a charge of 
. This means that zinc has been oxidized in the reaction; its oxidation number increased due to a loss of electrons.
Copper originally has an oxidation state of 
, but changes to its elemental form as a product. This gives copper a final oxidation state of zero. Since it has gained electrons, copper has been reduced.
Sulfur remains in the sulfate complex ion, which retains its overall 
charge throughout the reaction. It is neither oxidized, nor reduced.
For any oxidation-reduction reaction, the oxidized atom will lose electrons and the reduced atom will gain electrons. Zinc is originally in elemental form, so it has an initial oxidation state of zero. As a product, it has a charge of
Copper originally has an oxidation state of
Sulfur remains in the sulfate complex ion, which retains its overall
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Consider the following reaction:
Which of the following substances is the oxidizing agent?
Consider the following reaction:
Which of the following substances is the oxidizing agent?
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In an oxidation-reduction reaction, the oxidizing agent is the reactant that accepts electrons, becoming reduced. The oxidizing or reducing agent is always the whole reagent, and is never just the atom in the reagent that is being oxidized or reduced.
is the reagent that accepts two electrons from elemental zinc. This allows zinc to become oxidized, changing oxidation state from zero to 
. Copper accepts these electrons, changing from an oxidation state of 
to zero. As a result, we say that 
is the oxidizing agent for the reaction.
In an oxidation-reduction reaction, the oxidizing agent is the reactant that accepts electrons, becoming reduced. The oxidizing or reducing agent is always the whole reagent, and is never just the atom in the reagent that is being oxidized or reduced.
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In this reaction, electrons are transferred from to .
In this reaction, electrons are transferred from to .
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A transfer of electrons indicates an oxidation-reduction reaction. The element losing electrons is oxidized, while the element gaining electrons is reduced.
Calcium is initially a neutral solid, but as a product has a charge of 
. Calcium's charge increased, meaning it must have lost electrons.
Hydrogen initially has a charge of 
, but as a product is a neutral diatomic gas. Hydrogen's charge decreased, meaning it must have gained electrons.
We can thus conclude that calcium was oxidized and hydrogen was reduced, indicating that electrons were transferred from calcium to hydrogen.
The charge on chlorine remains 
throughout the entire reaction.
A transfer of electrons indicates an oxidation-reduction reaction. The element losing electrons is oxidized, while the element gaining electrons is reduced.
Calcium is initially a neutral solid, but as a product has a charge of
Hydrogen initially has a charge of
We can thus conclude that calcium was oxidized and hydrogen was reduced, indicating that electrons were transferred from calcium to hydrogen.
The charge on chlorine remains
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What does oxidation mean?
What does oxidation mean?
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Think "OIL RIG" Oxidation Is Loss of electrons, Reduction Is Gain of electrons. The loss and gain of electrons is what changes the charge of the atom or molecule. In redox reactions, electrons are transferred. Changing the number of protons changes the identity of the element ,which is not the case. Since chemical reactions involve valence electrons, the nucleus is unchanged.
Think "OIL RIG" Oxidation Is Loss of electrons, Reduction Is Gain of electrons. The loss and gain of electrons is what changes the charge of the atom or molecule. In redox reactions, electrons are transferred. Changing the number of protons changes the identity of the element ,which is not the case. Since chemical reactions involve valence electrons, the nucleus is unchanged.
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Oomycetes of the genus Phytophthora are capable of causing economic damage by destroying crops. The name Phytopthora from the Greek phyton = plant, and phthora = destruction literally means plant-destroyer. However, chemists may battle their destructive effects.
The compound named copper(II) carbonate can be used to destroy the plant-destroyer, and can be produced as shown in the following equation:
What is the net ionic equation for the given reaction that produces copper(II) carbonate?
Oomycetes of the genus Phytophthora are capable of causing economic damage by destroying crops. The name Phytopthora from the Greek phyton = plant, and phthora = destruction literally means plant-destroyer. However, chemists may battle their destructive effects.
The compound named copper(II) carbonate can be used to destroy the plant-destroyer, and can be produced as shown in the following equation:
What is the net ionic equation for the given reaction that produces copper(II) carbonate?
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An ionic equation is a chemical equation in which ionic compounds in an aqueous solution are written as dissociated ions.
A complete ionic equation shows all the ions present in the solution (which includes both the reactive and spectator ions), as the dissociated ions. The complete ionic equation for this problem's reaction is:
It is worth noting that in a complete ionic equation, it becomes readily apparent which ions are involved in the oxidation-reduction reaction, and which ions are the spectator ions (those that do not change during the reaction). For example since 
and 
are present on both sides of the reaction, they are spectator ions that go through the reaction unchanged. Also because the 
and 
are only present as dissolved ions on the reactants side of the equation and form the solid precipitate 
on the product side, they are the reactive species in this chemical reaction.
The net ionic equation shows only the reactive ions in solution and the product(s) formed by them. Therefore a net ionic equation can most simply be made by looking at the complete ionic equation and omitting the spectator ions as shown below:
Net ionic equation:
An ionic equation is a chemical equation in which ionic compounds in an aqueous solution are written as dissociated ions.
A complete ionic equation shows all the ions present in the solution (which includes both the reactive and spectator ions), as the dissociated ions. The complete ionic equation for this problem's reaction is:
It is worth noting that in a complete ionic equation, it becomes readily apparent which ions are involved in the oxidation-reduction reaction, and which ions are the spectator ions (those that do not change during the reaction). For example since
The net ionic equation shows only the reactive ions in solution and the product(s) formed by them. Therefore a net ionic equation can most simply be made by looking at the complete ionic equation and omitting the spectator ions as shown below:
Net ionic equation:
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Which statement about the reaction equation is correct?
Which statement about the reaction equation is correct?
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is converted to 
. Thus, an additional oxygen has been added to the original molecule, thus was oxidized. The substance that is oxidized is also called the reducing agent because it causes the reduction of the other molecule to which the oxygen originally was bound 
, which is the oxidizing agent.
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In the following reaction, which compound is being oxidized?
In the following reaction, which compound is being oxidized?
Tap to reveal answer
Hydrogen doesn't change. Cu2+ doesn't change (partnered with S2- then with SO42-). Sulfur goes from S2- and S6+(paired with 6 O2- with a 2– charge), showing an oxidation. Nitrogen goes from N5+ to N2+ meaning it was reduced.
Hydrogen doesn't change. Cu2+ doesn't change (partnered with S2- then with SO42-). Sulfur goes from S2- and S6+(paired with 6 O2- with a 2– charge), showing an oxidation. Nitrogen goes from N5+ to N2+ meaning it was reduced.
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Which of the following reactions involves the transfer of electrons?
Which of the following reactions involves the transfer of electrons?
Tap to reveal answer
Redox reactions occur when one species is oxidized—loses electrons—and another is reduced—gains electrons. Thus, this is the only one of the given options that involves the transfer of electrons.
Redox reactions occur when one species is oxidized—loses electrons—and another is reduced—gains electrons. Thus, this is the only one of the given options that involves the transfer of electrons.
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Consider the following reaction:
What is the oxidizing agent, and what is the reducing agent?
Consider the following reaction:
What is the oxidizing agent, and what is the reducing agent?
Tap to reveal answer
Let's break down the reaction into two separate reactions:
and
We can see that copper loses electrons, while silver gains electrons. Recall that oxidation is loss and reduction is gain, with regard to electrons. Copper is oxidized and silver is reduced.
However, this question asks for the oxidizing agent and reducing agent. Recall that the oxidizing agent is reduced, while the reducing agent is oxidized. Since copper is oxidized, it is the reducing agent. Similarly, since silver is reduced, it is the oxidizing agent.
Let's break down the reaction into two separate reactions:
We can see that copper loses electrons, while silver gains electrons. Recall that oxidation is loss and reduction is gain, with regard to electrons. Copper is oxidized and silver is reduced.
However, this question asks for the oxidizing agent and reducing agent. Recall that the oxidizing agent is reduced, while the reducing agent is oxidized. Since copper is oxidized, it is the reducing agent. Similarly, since silver is reduced, it is the oxidizing agent.
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Which statement about this reaction is FALSE?
Which statement about this reaction is FALSE?
Tap to reveal answer
In Cr2O3, Cr has a charge of +3. The chromium metal product is neutral, and therefore has a charge of 0. So, Cr is reduced from +3 to 0.
Remember, OIL RIG. Oxidation Is Loss (of electrons) and Reduction Is Gain (of electrons).
In Cr2O3, Cr has a charge of +3. The chromium metal product is neutral, and therefore has a charge of 0. So, Cr is reduced from +3 to 0.
Remember, OIL RIG. Oxidation Is Loss (of electrons) and Reduction Is Gain (of electrons).
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Methane combusts in the presence of oxygen according to the following reaction:
Which of the following statements is true concerning the reaction?
Methane combusts in the presence of oxygen according to the following reaction:
Which of the following statements is true concerning the reaction?
Tap to reveal answer
By comparing the oxidation number of an atom as a reactant and its oxidation number as a product, we can determine if the atom has been oxidized or reduced. In increase in oxidation number indicates a loss of electrons, or oxidation. A decrease in oxidation number signals a gain of electrons, or reduction.
For electrochemistry, you should familiarize yourself with the traditional oxidation states of hydrogen , halogens , oxygen , and elemental atoms .
Carbon is initially in the form of methane, meaning that it is attached to four hydrogen atoms. The molecule is neutral, and each hydrogen has an oxidation number of . Carbon must have an initial oxidation state of in order to balance the molecular charge.
In the a product, carbon is attached to two oxygens, each with a charge of . Again, the molecule is neutral, so carbon must balance these charges. This means that carbon's final oxidation state is .
Since carbon went from an oxidation state of to , we can conclude that carbon has been oxidized in the reaction.
By comparing the oxidation number of an atom as a reactant and its oxidation number as a product, we can determine if the atom has been oxidized or reduced. In increase in oxidation number indicates a loss of electrons, or oxidation. A decrease in oxidation number signals a gain of electrons, or reduction.
For electrochemistry, you should familiarize yourself with the traditional oxidation states of hydrogen
Carbon is initially in the form of methane, meaning that it is attached to four hydrogen atoms. The molecule is neutral, and each hydrogen has an oxidation number of
In the a product, carbon is attached to two oxygens, each with a charge of
Since carbon went from an oxidation state of
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Consider the following reaction:
Which of the following statements is true?
Consider the following reaction:
Which of the following statements is true?
Tap to reveal answer
For any oxidation-reduction reaction, the oxidized atom will lose electrons and the reduced atom will gain electrons. Zinc is originally in elemental form, so it has an initial oxidation state of zero. As a product, it has a charge of . This means that zinc has been oxidized in the reaction; its oxidation number increased due to a loss of electrons.
Copper originally has an oxidation state of , but changes to its elemental form as a product. This gives copper a final oxidation state of zero. Since it has gained electrons, copper has been reduced.
Sulfur remains in the sulfate complex ion, which retains its overall charge throughout the reaction. It is neither oxidized, nor reduced.
For any oxidation-reduction reaction, the oxidized atom will lose electrons and the reduced atom will gain electrons. Zinc is originally in elemental form, so it has an initial oxidation state of zero. As a product, it has a charge of
Copper originally has an oxidation state of
Sulfur remains in the sulfate complex ion, which retains its overall
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Consider the following reaction:
Which of the following substances is the oxidizing agent?
Consider the following reaction:
Which of the following substances is the oxidizing agent?
Tap to reveal answer
In an oxidation-reduction reaction, the oxidizing agent is the reactant that accepts electrons, becoming reduced. The oxidizing or reducing agent is always the whole reagent, and is never just the atom in the reagent that is being oxidized or reduced.
is the reagent that accepts two electrons from elemental zinc. This allows zinc to become oxidized, changing oxidation state from zero to . Copper accepts these electrons, changing from an oxidation state of to zero. As a result, we say that is the oxidizing agent for the reaction.
In an oxidation-reduction reaction, the oxidizing agent is the reactant that accepts electrons, becoming reduced. The oxidizing or reducing agent is always the whole reagent, and is never just the atom in the reagent that is being oxidized or reduced.
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In this reaction, electrons are transferred from to .
In this reaction, electrons are transferred from to .
Tap to reveal answer
A transfer of electrons indicates an oxidation-reduction reaction. The element losing electrons is oxidized, while the element gaining electrons is reduced.
Calcium is initially a neutral solid, but as a product has a charge of . Calcium's charge increased, meaning it must have lost electrons.
Hydrogen initially has a charge of , but as a product is a neutral diatomic gas. Hydrogen's charge decreased, meaning it must have gained electrons.
We can thus conclude that calcium was oxidized and hydrogen was reduced, indicating that electrons were transferred from calcium to hydrogen.
The charge on chlorine remains throughout the entire reaction.
A transfer of electrons indicates an oxidation-reduction reaction. The element losing electrons is oxidized, while the element gaining electrons is reduced.
Calcium is initially a neutral solid, but as a product has a charge of
Hydrogen initially has a charge of
We can thus conclude that calcium was oxidized and hydrogen was reduced, indicating that electrons were transferred from calcium to hydrogen.
The charge on chlorine remains
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What does oxidation mean?
What does oxidation mean?
Tap to reveal answer
Think "OIL RIG" Oxidation Is Loss of electrons, Reduction Is Gain of electrons. The loss and gain of electrons is what changes the charge of the atom or molecule. In redox reactions, electrons are transferred. Changing the number of protons changes the identity of the element ,which is not the case. Since chemical reactions involve valence electrons, the nucleus is unchanged.
Think "OIL RIG" Oxidation Is Loss of electrons, Reduction Is Gain of electrons. The loss and gain of electrons is what changes the charge of the atom or molecule. In redox reactions, electrons are transferred. Changing the number of protons changes the identity of the element ,which is not the case. Since chemical reactions involve valence electrons, the nucleus is unchanged.
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