Electrochemistry - Physical Chemistry
Card 0 of 15
A battery converts __________ energy to __________ energy.
A battery converts __________ energy to __________ energy.
Electronic devices such as cell phones utilize batteries for power. A discharging battery converts the chemical energy associated with redox reactions to electrical energy that can be utilized to power the device. Kinetic energy is the energy associated with motion and is irrelevant to this question.
Electronic devices such as cell phones utilize batteries for power. A discharging battery converts the chemical energy associated with redox reactions to electrical energy that can be utilized to power the device. Kinetic energy is the energy associated with motion and is irrelevant to this question.
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Which of the following statements about a charging battery is true?
Which of the following statements about a charging battery is true?
A charging battery behaves as an electrolytic cell. The process involves a nonspontaneous reaction; therefore, energy input is needed for charging a battery. This energy is provided by the electrical outlets that we use to charge our electronic devices, such as cell phones. Since it is nonspontaneous, the reaction occurring during charging has a positive Gibbs free energy.
Oxidation always occurs at the anode and reduction always occurs at the cathode, regardless of the type of cell. As mentioned previously, the charging battery requires energy input and behaves as an electrolytic cell. Exothermic reactions are characterized by a negative change in enthalpy. A reaction happening in an electrolytic cell is nonspontaneous. This means that the Gibbs free energy is always negative; however, other thermodynamic variables such as enthalpy and entropy can be either positive or negative.
A charging battery behaves as an electrolytic cell. The process involves a nonspontaneous reaction; therefore, energy input is needed for charging a battery. This energy is provided by the electrical outlets that we use to charge our electronic devices, such as cell phones. Since it is nonspontaneous, the reaction occurring during charging has a positive Gibbs free energy.
Oxidation always occurs at the anode and reduction always occurs at the cathode, regardless of the type of cell. As mentioned previously, the charging battery requires energy input and behaves as an electrolytic cell. Exothermic reactions are characterized by a negative change in enthalpy. A reaction happening in an electrolytic cell is nonspontaneous. This means that the Gibbs free energy is always negative; however, other thermodynamic variables such as enthalpy and entropy can be either positive or negative.
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Lithium batteries consist of lithium compounds and manganese dioxide. The reduction potential for lithium is 
, whereas the reduction potential for manganese dioxide is 
. Which of the following reaction(s) occur(s) when a lithium battery is discharging?
I. Oxidation of manganese
II. Reduction of lithium
III. Oxidation of lithium
Lithium batteries consist of lithium compounds and manganese dioxide. The reduction potential for lithium is
I. Oxidation of manganese
II. Reduction of lithium
III. Oxidation of lithium
A discharging battery behaves like a galvanic cell; therefore, it is characterized by a spontaneous reaction. This means that the reaction happening in a discharging battery has a positive standard reaction potential. Given the information in the question, we will get a positive standard reaction potential if the lithium atom is oxidized (half reaction potential = 
) and the manganese ion is reduced (half reaction potential = 
). The total standard reaction potential is the sum of the half reaction potentials, 
. The oxidation of manganese and the reduction of lithium will yield a negative potential, not characteristic of a discharging battery. Note that one reaction has to be oxidation and one reaction has to be reduction.
A discharging battery behaves like a galvanic cell; therefore, it is characterized by a spontaneous reaction. This means that the reaction happening in a discharging battery has a positive standard reaction potential. Given the information in the question, we will get a positive standard reaction potential if the lithium atom is oxidized (half reaction potential =
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A charging battery is acting as a(n) __________ cell and a discharging battery is acting as a(n) __________ cell.
A charging battery is acting as a(n) __________ cell and a discharging battery is acting as a(n) __________ cell.
A charging battery consumes energy from a power source like an electrical outlet, whereas a discharging battery releases energy and powers a device; therefore, a charging battery behaves as an electrolytic cell whereas a discharging battery behaves as a galvanic cell.
A charging battery consumes energy from a power source like an electrical outlet, whereas a discharging battery releases energy and powers a device; therefore, a charging battery behaves as an electrolytic cell whereas a discharging battery behaves as a galvanic cell.
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Listed below are standard reduction potentials for a few elements.
Lithium: 
Iron (with 
oxidation state): 
Aluminum: 
Given this information, which of the following redox reactions can be found in a galvanic cell?
I. 
II. 
III. 
Listed below are standard reduction potentials for a few elements.
Lithium:
Iron (with
Aluminum:
Given this information, which of the following redox reactions can be found in a galvanic cell?
I.
II.
III.
Galvanic cells are electrochemical cells that are characterized by a spontaneous redox reaction. To solve this question, we need to find the standard potential for each of the given reactions. Note that each reaction is a redox reaction; therefore, there is an oxidation half-reaction and a reduction half-reaction for each one.
The first reaction has a ferrous ion being reduced (gaining electrons) and lithium being oxidized (losing electrons). From the given information, we can deduce the standard potential for each half-reaction. The standard potential for reduction of iron is 
. Since the given standard potentials are for "reduction," the oxidation of iron is the opposite of the given value: 
. The total standard potential for this reaction is the sum of the standard potential for the half-reaction; therefore, the standard reaction potential for the first reaction is:
Since its standard reaction potential is positive, this reaction is spontaneous and occurs in a galvanic cell.
The second reaction has aluminum being oxidized (
) and a ferrous ion being reduced (
). The standard reaction potential is 
; therefore, this reaction can also occur in a galvanic cell.
The third reaction has a lithium ion being reduced (
) and an aluminum being oxidized (
). The standard reduction potential is 
; therefore, this reaction is nonspontaneous and cannot occur in a galvanic cell.
Galvanic cells are electrochemical cells that are characterized by a spontaneous redox reaction. To solve this question, we need to find the standard potential for each of the given reactions. Note that each reaction is a redox reaction; therefore, there is an oxidation half-reaction and a reduction half-reaction for each one.
The first reaction has a ferrous ion being reduced (gaining electrons) and lithium being oxidized (losing electrons). From the given information, we can deduce the standard potential for each half-reaction. The standard potential for reduction of iron is
Since its standard reaction potential is positive, this reaction is spontaneous and occurs in a galvanic cell.
The second reaction has aluminum being oxidized (
The third reaction has a lithium ion being reduced (
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The Gibbs free energy of a redox reaction is __________ for a galvanic cell and is __________ for an electrolytic cell.
The Gibbs free energy of a redox reaction is __________ for a galvanic cell and is __________ for an electrolytic cell.
Gibbs free energy is the “free” energy available that can be used to perform useful work. A negative Gibbs free energy corresponds to a spontaneous reaction, whereas a positive Gibbs free energy corresponds to a nonspontaneous reaction. Recall that a galvanic cell involves a spontaneous reaction, whereas an electrolytic cell involves a nonspontaneous reaction; therefore, the Gibbs free energy of the reaction is negative for a galvanic cell and positive for an electrolytic cell.
Gibbs free energy is the “free” energy available that can be used to perform useful work. A negative Gibbs free energy corresponds to a spontaneous reaction, whereas a positive Gibbs free energy corresponds to a nonspontaneous reaction. Recall that a galvanic cell involves a spontaneous reaction, whereas an electrolytic cell involves a nonspontaneous reaction; therefore, the Gibbs free energy of the reaction is negative for a galvanic cell and positive for an electrolytic cell.
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Which of the following is true regarding an electrolytic cell?
Which of the following is true regarding an electrolytic cell?
An electrolytic cell utilizes energy to facilitate a nonspontaneous redox reaction. This is different from a galvanic cell, which releases energy from a spontaneous redox reaction. A shared characteristic of both cells is that the oxidation half-reaction always happens at the anode and the reduction half-reaction always happens at the cathode. Note that a redox reaction always has an oxidation half-reaction and a reduction half-reaction.
The entropy of the reaction is typically negative for a nonspontaneous reaction. This is not true for all cases; therefore, the entropy could be positive or negative for an electrolytic cell. Electroplating involves reduction reactions that convert metal ions into solid metal. This solid metal is coated onto a metal plate. Since this involves a reduction reaction, it occurs at the cathode.
An electrolytic cell utilizes energy to facilitate a nonspontaneous redox reaction. This is different from a galvanic cell, which releases energy from a spontaneous redox reaction. A shared characteristic of both cells is that the oxidation half-reaction always happens at the anode and the reduction half-reaction always happens at the cathode. Note that a redox reaction always has an oxidation half-reaction and a reduction half-reaction.
The entropy of the reaction is typically negative for a nonspontaneous reaction. This is not true for all cases; therefore, the entropy could be positive or negative for an electrolytic cell. Electroplating involves reduction reactions that convert metal ions into solid metal. This solid metal is coated onto a metal plate. Since this involves a reduction reaction, it occurs at the cathode.
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What type of energy input is required for a galvanic cell?
What type of energy input is required for a galvanic cell?
Recall that galvanic cells carry out spontaneous reactions; therefore, they do not require energy. They release free energy that can be used to do work such as powering an electrical device (like cell phones).
Electrolytic cells, on the other hand, require energy because they carry out nonspontaneous reactions. They require the input of electrical energy.
Recall that galvanic cells carry out spontaneous reactions; therefore, they do not require energy. They release free energy that can be used to do work such as powering an electrical device (like cell phones).
Electrolytic cells, on the other hand, require energy because they carry out nonspontaneous reactions. They require the input of electrical energy.
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What will happen when the two given half-cells are connected by a salt bridge to form a galvanic cell?
What will happen when the two given half-cells are connected by a salt bridge to form a galvanic cell?
has a higher standard reduction potential, and will therefore be reduced, meaning that lead will be oxidized. The anode is where oxidation takes place, and the cathode is where reduction occurs. Therefore, we assign the cathode to copper and the anode to lead.
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For an electrolytic cell containing the two half-cells shown, the __________ reaction will take place and the 
will be __________.
For an electrolytic cell containing the two half-cells shown, the __________ reaction will take place and the
In an electrolytic cell, the non-spontaneous reaction occurs. This means that Na is reduced (making it the cathode) and Mn is oxidized (making it the anode). The standard cell potential can then be calculated as follows:
In an electrolytic cell, the non-spontaneous reaction occurs. This means that Na is reduced (making it the cathode) and Mn is oxidized (making it the anode). The standard cell potential can then be calculated as follows:
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A 
current is passed through a silver ion solution. How much silver is deposited after 10 minutes?
A
First we need to convert minutes to seconds (10min=600s), and knowing that 
, we can calculate the amount of silver deposited as follows:
If we follow the units carefully, we see that all of the units cancel out to give us a value in grams of silver, which is what we are looking for.
First we need to convert minutes to seconds (10min=600s), and knowing that
If we follow the units carefully, we see that all of the units cancel out to give us a value in grams of silver, which is what we are looking for.
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Which of the following periodic table groups typically undergo reduction reactions?
Which of the following periodic table groups typically undergo reduction reactions?
Reduction reactions are characterized by a gain of electrons whereas oxidation reactions are characterized by a loss of electrons. Recall that elements on the right side of the periodic table have the tendency to gain electrons to complete the octet. Groups such as chalcogens (group VI) and halogens (group VII) have six and seven valence electrons, respectively; therefore, they only need a few electrons to have eight valence electrons and complete the octet. Since halogens tend to gain electrons, they typically undergo reduction.
Alkaline earth metals (group II) and transition metals have few valence electrons; therefore, they tend to lose electrons and undergo oxidation. Noble gases are nonreactive elements and do not undergo reduction or oxidation.
Reduction reactions are characterized by a gain of electrons whereas oxidation reactions are characterized by a loss of electrons. Recall that elements on the right side of the periodic table have the tendency to gain electrons to complete the octet. Groups such as chalcogens (group VI) and halogens (group VII) have six and seven valence electrons, respectively; therefore, they only need a few electrons to have eight valence electrons and complete the octet. Since halogens tend to gain electrons, they typically undergo reduction.
Alkaline earth metals (group II) and transition metals have few valence electrons; therefore, they tend to lose electrons and undergo oxidation. Noble gases are nonreactive elements and do not undergo reduction or oxidation.
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A researcher has two compounds. Compound A is manganese dioxide (
) and compound B is potassium permanganate (
). A reaction involving the conversion of manganese in Compound A to manganese in Compound B can be classified as which of the following reactions?
A researcher has two compounds. Compound A is manganese dioxide (
For this problem, we need to figure out the oxidation states of manganese in each compound. Oxygen typically has an oxidation number of 
and potassium has an oxidation number of 
. For Compound A, there are two oxygen molecules; therefore, oxygen contributes a total charge of 
. Since manganese dioxide is a neutral molecule, the manganese in it will have an oxidation number of 
. For Compound B, four oxygen atoms contribute a charge of 
whereas one potassium atom contributes a charge of 
; therefore, the manganese in potassium permanganate will have an oxidation number of 
. Conversion of manganese from Compound A to manganese in Compound B involves the removal of electrons—three electrons, specifically, because its charge has to change from 
to 
; therefore, this reaction is characterized as an oxidation reaction.
For this problem, we need to figure out the oxidation states of manganese in each compound. Oxygen typically has an oxidation number of
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Oxidation reactions __________ electrons and reduction reactions __________ electrons.
Oxidation reactions __________ electrons and reduction reactions __________ electrons.
Oxidation involves a loss of electrons whereas reduction involves a gain of electrons. This means that oxidation generates electrons as products whereas reduction consumes electrons as reactants. Note that oxidation and reduction reactions can be distinguished by looking at oxidation states. If the oxidation state of an atom becomes more positive, then it underwent an oxidation reaction, and if the oxidation state becomes more negative, then that atom underwent a reduction reaction.
Oxidation involves a loss of electrons whereas reduction involves a gain of electrons. This means that oxidation generates electrons as products whereas reduction consumes electrons as reactants. Note that oxidation and reduction reactions can be distinguished by looking at oxidation states. If the oxidation state of an atom becomes more positive, then it underwent an oxidation reaction, and if the oxidation state becomes more negative, then that atom underwent a reduction reaction.
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Which of the following reactions involves both reduction and oxidation reactions?
Which of the following reactions involves both reduction and oxidation reactions?
A reaction that has both reduction and oxidation half reaction is called a redox reaction. It involves one or more atoms gaining electrons (reduction) and one or more atoms losing electrons (oxidation). Recall that single displacement reactions involve the replacement of an element in a compound with another element. An example of single replacement reaction is shown below:
In this reaction, a sodium atom replaces a calcium atom in calcium sulfate. If we calculate the oxidation numbers for sodium and calcium, we can see that sodium loses an electron (the oxidation state goes from 
to 
) whereas the calcium ion gains two electrons (goes from 
to 
); therefore, this is a redox reaction. All single displacement reactions follow this general trend and are characterized as redox reactions.
Reaction of sodium chloride and calcium sulfate is as follows:
If we calculate the oxidation state of each atom we will notice that oxidation number doesn’t change; therefore, this isn’t a redox reaction.
A reaction that has both reduction and oxidation half reaction is called a redox reaction. It involves one or more atoms gaining electrons (reduction) and one or more atoms losing electrons (oxidation). Recall that single displacement reactions involve the replacement of an element in a compound with another element. An example of single replacement reaction is shown below:
In this reaction, a sodium atom replaces a calcium atom in calcium sulfate. If we calculate the oxidation numbers for sodium and calcium, we can see that sodium loses an electron (the oxidation state goes from
Reaction of sodium chloride and calcium sulfate is as follows:
If we calculate the oxidation state of each atom we will notice that oxidation number doesn’t change; therefore, this isn’t a redox reaction.
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