Electrochemical Cells: Components and Reactions; Standard Cells: Equations and C
ID: 1044895 • Letter: E
Question
Electrochemical Cells: Components and Reactions; Standard Cells: Equations and Cell Potential (Ec-Ea), Identify Features; Nerst: Half Cell: Vary Concentration, Pressure
1. Electrochemical Cells:
a. A voltaic cell is constructed in which the anode is a Mg|Mg2+ half cell and the cathode is a Cr2+|Cr3+ half cell. The half-cell compartments are connected by a salt bridge.
(Use the lowest possible coefficients. Use the pull-down boxes to specify states such as (aq) or (s). If a box is not needed, leave it blank.)
The anode reaction is: ___ + ___ ------> ___ + ___
The cathode reaction is: ___ + ___ -------> ___ + ___
The net cell reaction is: ___ + ___ ------> ___ + ___
In the external circuit, electrons migrate _____ (from or to) the Cr2+|Cr3+electrode _____ (from or to) the Mg|Mg2+ electrode.
In the salt bridge, anions migrate _____ (from or to) the Cr2+|Cr3+ compartment _____ (from or to) the Mg|Mg2+ compartment.
b. A voltaic cell is constructed in which the following cell reaction occurs. The half-cell compartments are connected by a salt bridge.
Sn2+(aq) + Zn(s) -----> Sn(s) + Zn2+(aq)
The anode reaction is: ___ + ___ ------> ___ + ___
The cathode reaction is: ___ + ___ ------> ____ + ____
In the external circuit, electrons migrate _____ (from or to) the Sn|Sn2+ electrode _____ (from or to) the Zn|Zn2+ electrode.
In the salt bridge, anions migrate _____ (from or to) the Sn|Sn2+ compartment _____ (from or to) the Zn|Zn2+ compartment.
c. A voltaic cell is constructed in which the anode is a Cu+|Cu2+ half cell and the cathode is a I-|I2 half cell. The half-cell compartments are connected by a salt bridge.
(Use the lowest possible coefficients. Use the pull-down boxes to specify states such as (aq) or (s). If a box is not needed, leave it blank.)
The anode reaction is: ___ + ___ ----> ___ + ___
The cathode reaction is: ___ + ___ ----> ___ + ___
The net cell reaction is: ___ + ___ ------> ___ + ___
In the external circuit, electrons migrate _____ (from or to) the I-|I2 electrode _____ (from or to) the Cu+|Cu2+ electrode.
In the salt bridge, anions migrate _____ (from or to) the Cu+|Cu2+ compartment _____ (from or to) the I-|I2 compartment.
2. Standard Cells:
a. A voltaic cell is constructed from a standard Cd2+|Cd half cell (E°red = -0.403V) and a standard Cr3+|Cr2+ half cell (E°red = -0.410V).
(Use the lowest possible coefficients. Use the pull-down boxes to specify states such as (aq) or (s). If a box is not needed, leave it blank.)
The anode reaction is: ___ + ___ ----> ___ + ___
The spontaneous cell reaction is: ___ + ___ -----> ___ + ___
The cathode reaction is: ___ + ___ ----> ___ + ___
The cell voltage is ___ V.
b. A voltaic cell is constructed from a standard Zn2+|Zn half cell (E°red = -0.763V) and a standard Sn2+|Sn half cell (E°red = -0.140V).
The anode reaction is: ___ + ___ ------> ___ + ___
The cathode reaction is: ___ + ___ ------> ___ + ___
The spontaneous cell reaction is: ___ + ___ ------> ___ + ___
The cell voltage is ___ V
c. A voltaic cell is constructed from a standard Sn2+|Sn half cell (E°red = -0.140V) and a standard F2|F- half cell (E°red = 2.870V).
The anode reaction is: ___ + ___ ------> ___ + ___
The cathode reaction is: ___ + ___ ------> ___ + ___
The spontaneous cell reaction is: ___ + ___ ------> ___ + ___
The cell voltage is ___ V
d. A standard galvanic cell is constructed with Mg2+ | Mg and Cr3+ | Cr2+half cell compartments connected by a salt bridge. Which of the following statements are correct?
Hint: Refer to a table of standard reduction potentials.
(Choose all that apply.)
As the cell runs, anions will migrate from the Cr3+|Cr2+compartment to the Mg2+|Mg compartment.
The anode compartment is the Mg2+|Mg compartment.
Cr3+ is reduced at the cathode.
In the external circuit, electrons flow from the Cr3+|Cr2+compartment to the Mg2+|Mg compartment.
Cr2+ is oxidized at the anode.
e. A standard galvanic cell is constructed in which a H+ | H2 half cell acts as the cathode. Which of the following statements are correct?
Hint: Refer to a table of standard reduction potentials.
(Choose all that apply.)
The cathode reaction is 2H+ + 2e- -> H2.
The anode compartment could be Fe3+|Fe2+.
In the external circuit, electrons flow from the H+|H2 compartment to the other compartment.
The cathode reaction is H2 -> 2H+ + 2e-.
As the cell runs, anions will migrate from the H+|H2 compartment to the other compartment.
f. A standard galvanic cell is constructed in which a Cu2+ | Cu+ half cell acts as the cathode. Which of the following statements are correct?
Hint: Refer to a table of standard reduction potentials.
(Choose all that apply.)
The anode compartment could be Fe3+|Fe2+.
The cathode reaction is Cu2+ + e- -> Cu+
Cu+ is oxidized at the cathode.
Cu2+ is reduced at the cathode.
As the cell runs, anions will migrate from the Cu2+|Cu+compartment to the other compartment.
3. Nerst Half Cell: Find the reduction potential for the following non standard half cell at 298K for each.
a. Cr3+ (9.15×10-3M) + e- -------> Cr2+ (1.78M)
b. Cd2+ (2.63×10-3M) + 2e- ------> Cd (s)
c. F2 (3.87×10-3atm) + 2e- --------> 2F- (1.46M)
Explanation / Answer
Q1) Electrochemical cell:
a) Anode: Mg|Mg2+
Cathode: Cr2+|Cr3+
Anode reaction: Mg(s) ---->Mg2+(aq) +2e (oxidation)
Cathode reaction: 2Cr3+(aq) + 2e ----->2Cr2+(aq)
Net rxn: Mg(s)+2Cr3+(aq) ---->Mg2+(aq)+2Cr2+(aq)
In the external circuit, electrons migrate from anode half-cell Mg|Mg2+ to cathode half-cell ,Cr2+|Cr3+
In the salt bridge ,anions migrate from Cr2+|Cr3+ compartment to Mg|Mg2+ compartment.
b) Sn2+(aq) +Zn(s) --->Sn(s) +Zn2+(aq)
Anode reaction: Zn(s) ---->Zn2+(aq) +2e (oxidation)
Cathode reaction: Sn2+(aq) + 2e ----->Sn(s)(aq)
In the external circuit, electrons migrate from anode half-cell Zn(s)|Zn2+(aq) to Sn2+(aq)|Sn(s)
In the salt bridge ,anions migrate from Sn(s)|Sn2+(aq) compartment to Zn|Zn2+ compartment.
(c)
Anode: Cu+|Cu2+
Aode reaction: Cu+(aq) +e -->Cu2+(aq)
Cathode: I-| I2
cathode reaction: 2I-(aq) ------>I2(aq) +2e
Net cell rxn: Cu+(aq) + 2I-(aq) ---->Cu2+(aq)+I2(aq)
In the external circuit, electrons migrate from anode half-cell Cu+|Cu2+(aq) to I-| I2
In the salt bridge ,anions migrate from I-| I2(aq) compartment to Cu+|Cu2+(aq)compartment.
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