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Questions and Answers
What process occurs at the anode in an electrochemical cell?
What process occurs at the anode in an electrochemical cell?
- Cu is deposited from Cu2+.
- Zn is oxidized to Zn2+ and electrons are released. (correct)
- The cell voltage is measured.
- Reduction occurs as Cu2+ accepts electrons.
What role does the Cu2+ ion play in its reduction half-reaction?
What role does the Cu2+ ion play in its reduction half-reaction?
- Cathode
- Reducing agent
- Anode
- Oxidizing agent (correct)
What does the notation 'Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu(s)' represent?
What does the notation 'Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu(s)' represent?
- The reaction at the cathode only.
- The conductivity of the circuit.
- The overall charge of the electrochemical cell.
- The phase boundary between solids and solutions. (correct)
Why does standard cell potential (E°cell) need to be measured relative to a standard electrode?
Why does standard cell potential (E°cell) need to be measured relative to a standard electrode?
Which equation represents oxidation in the context of electrochemical cells?
Which equation represents oxidation in the context of electrochemical cells?
How is the overall cell potential calculated in an electrochemical cell?
How is the overall cell potential calculated in an electrochemical cell?
What indicates a product-favored reaction when analyzing cell voltage?
What indicates a product-favored reaction when analyzing cell voltage?
What happens to the concentration of reactants and products when conditions deviate from standard conditions?
What happens to the concentration of reactants and products when conditions deviate from standard conditions?
What is the standard cell potential for the reaction involving Zn(s) and Cu2+(aq)?
What is the standard cell potential for the reaction involving Zn(s) and Cu2+(aq)?
What role does the salt bridge play in an electrochemical cell?
What role does the salt bridge play in an electrochemical cell?
In an electrochemical cell, what species undergoes reduction at the cathode?
In an electrochemical cell, what species undergoes reduction at the cathode?
In the electrochemical reaction Cu2+ + 2e- → Cu, what process is occurring?
In the electrochemical reaction Cu2+ + 2e- → Cu, what process is occurring?
What effect does reversing a half-reaction have on its standard cell potential?
What effect does reversing a half-reaction have on its standard cell potential?
Which ion has the highest standard reduction potential in the provided table?
Which ion has the highest standard reduction potential in the provided table?
Which of the following conditions is part of standard cell potential measurement?
Which of the following conditions is part of standard cell potential measurement?
What is the standard reduction potential for the reaction of $ ext{H}_2 ext{O}_2(aq)$ reducing to $ ext{H}_2 ext{O}(l)$?
What is the standard reduction potential for the reaction of $ ext{H}_2 ext{O}_2(aq)$ reducing to $ ext{H}_2 ext{O}(l)$?
What is the primary purpose of a salt bridge in an electrochemical cell?
What is the primary purpose of a salt bridge in an electrochemical cell?
In the redox reaction involving N2 and S2-, what is being reduced?
In the redox reaction involving N2 and S2-, what is being reduced?
Which of the following correctly specifies the electron flow in a voltaic cell?
Which of the following correctly specifies the electron flow in a voltaic cell?
What does the anode represent in an electrochemical cell?
What does the anode represent in an electrochemical cell?
When balancing redox equations in basic solutions, what is the last step after equalizing the number of electrons?
When balancing redox equations in basic solutions, what is the last step after equalizing the number of electrons?
What is the chemical reaction that represents the standard process in electrochemical cells described in the content?
What is the chemical reaction that represents the standard process in electrochemical cells described in the content?
In the context of electrochemical cells, what role does the cathode serve?
In the context of electrochemical cells, what role does the cathode serve?
During the balancing of redox reactions, what is added to balance hydrogen atoms in acidic conditions?
During the balancing of redox reactions, what is added to balance hydrogen atoms in acidic conditions?
Study Notes
Electrochemical Cells
- An electrochemical cell is formed when two half-cells are connected, with each half-cell consisting of an electrode and a solution containing ions related to the electrode.
Voltaic Cell
- A voltaic cell is a type of electrochemical cell that produces electrical energy from a spontaneous chemical reaction.
- It is also called a galvanic cell or a battery.
Anode & Cathode
- The anode is where oxidation takes place, losing electrons (- charge). The cathode is where reduction takes place, gaining electrons (+ charge).
Salt Bridge
- A salt bridge connects the two half-cells of a voltaic cell allowing the flow of ions to maintain electrical neutrality.
- The salt bridge contains a solution of an inert electrolyte, like K2SO4, which prevents the build-up of charge in the half-cells.
Cell Notation
- Cell notation is a shorthand way to represent an electrochemical cell.
- For example: Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu (s) where (s) refers to a solid state, (aq) refers to aqueous state, | represents a phase boundary, and || represents a salt bridge.
Voltage Measurement
- Voltage depends on the type of cell and the chemistry involved, not the size of the cell.
- Standard voltage (E°) is measured when all solute concentrations are 1 M, or saturated when solubility is less than 1 M.
Cell Voltage
- Cell voltage (E°cell) is positive when products are favored and negative when reactants are favored.
- Absolute voltages cannot be measured, they are measured relative to a standard electrode.
Standard Hydrogen Electrode (SHE)
- This is a reference electrode with assigned potential E° = 0 V.
- The standard hydrogen electrode half-cell reaction is 2 H3O+(aq, 1M) + 2 e- H2(g, 1 bar) + 2 H2O (l)
Standard Reduction Potentials
- Standard reduction potentials (E°) are tabulated for various reduction half-reactions, allowing for the calculation of the standard cell potential (E°cell).
Cell Voltage Calculation
- The standard cell potential (E°cell) is calculated using the following formula: E°cell = E°cathode - E°anode.
- When an equation is reversed, the E° value is multiplied by -1.
- The E° for oxidation is the negative of its reduction potential.
Balancing Redox Reactions
- Redox reactions can be balanced in acidic or basic solutions.
- In basic solution, H+ ions are replaced with H2O and OH- ions.
Electrochemical Cells and Voltage
- Electrical work = charge x ΔEp = (number of e-) ΔEp
- SI Units: 1 coulomb (C) = 1 ampere x second = 1 As. 1 volt (V) = 1 J C-1.
- Cell voltage varies with conditions, but the standard voltage (E°) remains consistent under standard conditions.
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Description
This quiz covers the fundamentals of electrochemical cells, focusing on the workings of voltaic cells, their components such as anodes and cathodes, and the function of salt bridges. Test your understanding of cell notation and the chemical reactions that produce electrical energy.
