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63 Cards in this Set
- Front
- Back
- 3rd side (hint)
Oxidation |
The loss of electrons |
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Reduction |
The gain of elecrons |
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Oxidation-Reduction Reaction |
Reactions that occur when electrons are transfered from an atom that is oxidized to an atom that is reduced. |
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Electrochemistry |
The study of the relationship between electricity and chemical reactions. |
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Oxidation Number (Oxidation State) |
A positive or negative whole number assigned to an element in a molecule or ion on the basis of a set of formula rules; to some degree it reflects the positive or negative character of that atom. |
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In a redox reaction this must happen. |
Both oxidation and reaction must occur. |
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Oxidizing Agent (Oxidant) |
The substance that is reduced and thereby causes the oxidation of some other substance in an oxidation-reduction reaction. |
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Reducing Agent (Reductant) |
The substance that is oxidized and thereby causes the reduction of some other substance in an oxidation-reduction reaction. |
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Identify Oxidizing and Reducing Agents: Cd+NiO2+2H2O → Cd(OH)2+Ni(OH)2 |
Cd increases in oxidation state from 0 to +2 Ni decreases from +4 to +2 |
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Identify the Oxidizing and Reducing Agents 2H2O+All+MnO4^- → Al(OH)4^-+MnO2 |
Al is the reducing agent MnO4 is the oxidizing agent |
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Half Reaction |
An equation for either an oxidation or reduction that explicitly shows the electrons involved l, for example, Zn^2+ + 2e^- → Zn |
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Electrons are shown as products in what type of reactions? |
An Oxidation Half-Reactions |
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Electrons are shown as reactants in what type of reaction? |
A Reduction Half-Reaction |
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Equations that show either oxidation or reduction alone are called ___________. |
Half-Reactions |
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In the overall redox reaction, the number of electrons lost in the oxidation half-reaction must be _____________ to the number of electrons ___________ in reduction half-reaction. |
Equal; gained |
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What are the five steps for balancing a redox redaction that occurs in acidic solution ? |
1. Divide the equation into two half reactions 2. Balance each half-reaction 3. Multiply the half reactions to make the electron equal 4. Add the two half-reactions together 5. Check to make sure that atoms are balanced (If they're not you did something wrong) |
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How do you balance a half-reaction? |
First, balance the elements other than H and O. Next, balance the O atoms by adding H2O as needed. Then, balance the H atoms by adding H^+ as needed. Finally, balance the charge by adding e^- as needed. |
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Complete and balance this equation: MnO4^- + C2O4²^- → Mn²^+ + CO2 (Acidic Solution) |
16H^+ + 2MnO4^- + 5C2O4²^- → 2Mn²^+ + 8H2O + 10CO2 |
Page 847-848 in the AP Chemistry 11e textbook. |
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If the equation for a redox reaction is balanced, will free electrons appear in the equation as either reactants or products? |
No, because the electrons should have been completely canceled out in step 3 and 4 when balancing and adding the half-reactions. |
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Complete and balance the equation by the method of half-reactions: Cr2O7²^- + Cl^- → Cr³^+ + Cl2 (Acidic Solution) |
14H^+ + Cr2O7²^- + 6Cl^- → 2Cr³^+ + 7H2O + 3Cl2 |
Page 849 in the AP Chemistry 11e textbook |
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Complete and balance the equation by half-reaction method: Cu + NO3^- → Cu²^+ + NO2 (Acidic Solution) |
Cu + 4H^+ + 2NO3^- → Cu²^+ + 2NO2 + H2O |
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Complete and balance this equation by the half-reaction method: Mn²^+ + NaBiO3 → Bi³^+ + MnO4^- (Acidic Solution) |
2Mn²^+ + 5NaBiO3 +14H^+ → 2MnO4^- + 5Bi³^+ + 5Na^+ + 7H2O |
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If a redox reaction occurs in basic solution, the equation must be completed by using ________ and ________ rather than H^+ and H2O. |
OH^- and H2O |
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Complete and balance this equation for a redox reaction by half-reaction method: CN^- + MnO4^- → CNO^- + MnO2 (Basic Solution) |
3CN^- + H2O + 2MnO4 → 3CNO^- + 2MnO2 + OH^- |
Page 850 in the AP Chemistry 11e textbook. |
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Complete and balance this equation using the half-reaction method: NO2^- + Al → NH3 Al(OH)4^- (Basic Solution) |
NO2^- + 2Al + 5H2O + OH^- → NH3 + 2Al(OH)4^- |
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Complete and balance this reaction by using the half-reaction method: Cr(OH)3 + ClO^- → CrO4²^- + Cl2 (Basic Solution) |
2Cr(OH)3 +6ClO^- → 2CrO4²^- + 3Cl2 + 2OH^- + 2H2O |
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Voltaic (or Galvanic) Cell |
A device in which the transfer of electrons takes place through an external pathway rather than directly between reactants. |
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Electrodes |
Two solid metals that are connected by an external circuit. |
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Anode |
The electrode at which reduction occurs |
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Cathode |
The electrode at which oxidation occurs. |
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Half-Cells |
The two compartments of a voltaic cell |
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Anode is the _________ half-reaction. |
Oxidation |
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Cathode is the __________ half-reaction. |
Reduction |
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The oxidized electrode in a redox reaction gains or loses mass? |
Loses mass |
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The reduced electrode in a redox reaction gains or loses mass? |
Gains mass |
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______ always migrate to toward Anode and _______ always migrate to the Cathode. |
Anions; Cations |
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Why do anions in a salt bridge migrate toward the anode? |
To balance the charge in the anode compartment. |
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In a voltaic cell electrons flow from the _______ to the _______. |
Anode; Cathode |
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Is the Anode positive or negative? |
Negative |
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Is the Cathode positive or negative? |
Positive |
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There are two reactions in a voltaic cell: Zn → Zn²^+ + 2e^- ClO3^- 6H^+ + 6e^- → Cl^- + 3H2O Which reaction occur at the anode and which occurs at the cathode? |
Anode: Zn → Zn²^+ + 2e^- Cathode: ClO3^- 6H^+ + 6e^- → Cl^- + 3H2O |
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There are two reactions in a voltaic cell: Zn → Zn²^+ + 2e^- ClO3^- 6H^+ + 6e^- → Cl^- + 3H2O Which electrode is consumed in the cell reaction? |
The anode (Zn) is consumed in the cell reaction. |
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There are two reactions in a voltaic cell: Zn → Zn²^+ + 2e^- ClO3^- 6H^+ + 6e^- → Cl^- + 3H2O Which electrode is positive? |
The cathode (Cl) is positive. |
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The difference in potential energy per electrical charge between two electrodes is measured in units of ______? |
Volts |
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Volts (V) is the measure of ..... |
Electromotive Force (EMF) |
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Electromotive Force (EMF) |
A measure of the driving force, or electrical pressure, for the completion of an electrochemical reaction. Electromotive force is measured in volts: V = J/C. Also called the cell potential. |
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Electromotive force is also known as... |
Cell Potential |
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What is Ecell? |
The EMF of a cell. |
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For any cell reaction that proceeds spontaneously the cell potential is ___________? |
Positve |
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What is E°cell? |
The Standard EMF or Standard Cell Potential |
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What is Standard EMF? |
The EMF of a cell at standard conditions. (25°C, 1 atm, 1 M, etc.) |
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If the standard cell potential is +0.85V at 25°C, is the redox reaction of the cell spontaneous? |
Yes |
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What is E°red? |
Standard Reduction Potentials |
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What is the formula to calculate E°cell? |
E°cell = E°red (Cathode) - E°red (Anode) |
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For all spontaneous reactions at standard conditions, E°cell is greater than, equal to, or less than 0. |
E°cell > 0 |
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In reduction reaction the electrons appear on what side of the reaction. |
The reactant side (The left side) |
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Changing the stoichiometric coefficient in a half-reaction ___________ affect the value of the standard reduction potential. |
Does not |
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Zn + Cu²^+ → Zn²^+ + Cu; E°cell = 1.10V Given that the standard reduction potential of Zn²^+ to Zn is -0.76V, calculate the E°red for the reduction of Cu²^+ to Cu: Cu²^+ + 2e^- → Cu |
E°red (cathode) = 0.34V |
Page 858 in the AP Chemistry 11e textbook. |
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A voltaic cell is based on the half-reactions In^+ → Ln³^+ + 2e^- Br2 + 2e^- → 2Br^- The standard emf for this cell is 1.46V. Calculate the E°red using Appendix E |
E°red = 0.34V |
Page 858 in the AP Chemistry textbook. |
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Using the standard reduction table in Appendix E calculate the standard emf of this reaction: Cr2O7²^- + 14H^+ + 6I^- → 2Cr³^+ 3I2 + 7H2O |
E°cell = 0.79V |
Page 859 in the AP Chemistry 11e textbook. |
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Using Appendix E in the AP Chemistry 11e textbook, calculate the standard emf for a cell that employs the following overall reaction: 2Al + 3I2 → 2Al³^+ + 6I^- |
2.20V |
Page 859 in the AP Chemistry 11e textbook. |
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The more ________ the value of the E°red, the greater the driving force for reduction under standard conditions. |
Positive |
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The smaller the difference is between the standard reduction potentials of the cathode and anode, the ________ the driving force for the overall redox reaction. |
Smaller |
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