All AP Chemistry Resources
Example Questions
Example Question #141 : Thermochemistry And Kinetics
Consider the following electrolytic cell:
What happens at the anode in the electrolytic cell?
Nickel is reduced
Iron is reduced
Nickel is oxidized
Iron is oxidized
Nickel is oxidized
It does not matter if the cell is galvanic or electrolytic; oxidation will always take place at the anode. This means that the nickel loses two electrons and is oxidized at the anode to generate nickel ions.
Nickel ions and iron are products, and are neither oxidized nor reduced during the reaction. Iron ions are reduced at the cathode to generate the iron product.
Example Question #1 : Galvanic (Voltai) And Elecrolytic Cells
Consider the following reaction in a galvanic cell:
Which of the following takes place at the anode?
Copper is reduced
Zinc is reduced
Zinc is oxidized
Copper is oxidized
No reaction takes place at the anode
Zinc is oxidized
Oxidation takes place at the anode and reduction takes place at the cathode. You can remember this with the pneumonic "An Ox, Red Cat."
In the equation, zinc loses electrons. It goes from a neutral, elemental charge to a charge of . Since electrons are negative, a loss of electrons will cause an increase in charge. Because zinc loses electrons, it is oxidized. This will take place at the anode.
Example Question #2 : Galvanic (Voltai) And Elecrolytic Cells
Toward which pole do electrons travel in a galvanic cell?
Towards the cathode
Towards the anode
Towards the negative pole
More information is needed
Electrons do not travel; only the protons travel
Towards the cathode
Reduction always occurs at the cathode, and oxidation always occurs at the anode. Since reduction is the addition of electrons, the electrons must flow toward the site of reduction.
In a galvanic cell the positive charge is on the cathode, while the negative charge is on the anode. Since a galvanic cell has a positive potential and is spontaneous, electrons freely flow down their potential gradient. The electrons, which are negatively charged, are traveling towards the cathode, which is positive charged, since opposites attract.
Example Question #1 : Electrochemistry
Toward which pole do the electrons travel in an electrolytic cell?
Towards the positive pole
The electrons do not travel; only the protons travel
More information is needed
Towards the anode
Towards the cathode
Towards the cathode
Reduction always occurs at the cathode, and oxidation always occurs at the anode. Since reduction is the addition of electrons, electrons must travel toward the site of reduction.
In an electrolytic cell the negative charge is on the cathode, while the positive charge is on the anode. Since an electrolytic cell requires energy to perpetuate the reaction, we are pushing the electrons against their potential gradient. The electrons, which are negatively charged, are traveling towards the cathode, which is also negatively charged.
Example Question #2 : Electrochemistry
Which of the following differences between galvanic cells and electrolytic cells is false?
Electrolytic cells are non-spontaneous
Electrolytic cells have negative voltages
Electrolytic cells have a positive Gibb's free energy
Electrolytic cells have oxidation take place at the cathode
Electrolytic cells have oxidation take place at the cathode
Electrolytic cells use non-spontaneous reactions that require an external power source in order to proceed. The values between galvanic and electrolytic cells are opposite of one another. Galvanic cells have positive voltage potentials, while electrolytic voltage potentials are negative. Both types of cell, however, have oxidation occur at the cathode and reduction occur at the anode.
Example Question #3 : Galvanic (Voltai) And Elecrolytic Cells
What is true about the current flow in a galvanic cell?
It travels from cathode to anode
Galvanic cells do not have a current
It flows in the direction of electron flow
It travels from anode to cathode
It travels from cathode to anode
In a galvanic cell, the electrons will flow from the anode to the cathode; however, current travels in the opposite direction of the electrons by convention. In chemical cells, current is defined by the direction in which protons would flow. As a result, current flows from the cathode to the anode.
Keep in mind that reduction occurs at the cathode and oxidation occurs at the anode. Electrons are thus constantly moving from the anode to the cathode. Since the current will be opposite to the flow of electrons, we can conclude that it must flow from cathode to anode.
Example Question #4 : Galvanic (Voltai) And Elecrolytic Cells
The following galvanic cell is created:
Which of the following takes place at the cathode?
Gold loses electrons
Gold ions receive electrons
Copper gains electrons
Copper loses electrons
Gold ions receive electrons
Reduction always takes place at the cathode. This means that a substance is receiving electrons.
In the reaction, the gold ions are receiving electrons in order to create gold atoms. This takes place at the cathode.
Copper ions and gold are products, and will not be oxidized or reduced. Copper is reduced at the anode during this reaction.
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