Chemistry Unit 8
Answer correctly (oxidizes, reduces) for questions about a NiCd cell. As NiOOH 1.) oxidizes, it accepts electrons lost by the anode.The cadmium anode 2.) reduces, losing electrons that travel through a conductor into the electrical circuit.The Cd(OH)2 3.) reduces to cadmium metal and the Ni(OH)2 4.) oxidizes to NiOOH.
1.) oxidizes 2.) reduces 3.) reduces - this is wrong? 4.) oxidizes 50%
A substance called a(n) 1.) oxidizing agent has the potential to cause oxidation in another substance, but a substance with the potential to cause reduction in another substance is a(n) 2.) reducing agent.
1.) oxidizing 2.) reducing
A 1.) positive value for E0 indicates that a substance is more willing than hydrogen to accept electrons, and a 2.) negative value indicates that a substance is less willing than hydrogen to accept electrons.
1.) positive 2.) negative
An electrochemical cell that produces electric current by redox reactions that are not reversible is called a(n) 1.) primary voltaic cell, but a(n) 2.) secondary voltaic cell is an electrochemical cell that produces an electric current by reversible redox reactions.
1.) primary 2.) secondary
The negative ion of a strong oxidizing agent is a weak 1.) reducing agent, and the positive ion of a strong reducing agent is a weak 2.) oxidizing agent.
1.) reducing 2.) oxidizing
For electrons to flow from the oxidation half-cell through a conductor to the reduction half-cell, a(n) 1.) salt bridge must be placed between the two half-cells to allow 2.) ions to pass from one solution to another.
1.) salt 2.) ions
The three types of voltaic cells are primary cells, __________ cells, and _______ cells.
1.) secondary 2.) fuel
In an electrochemical cell, 1.) anode the is the electrode where oxidation takes place, and the 2.) cathode is where reduction takes place.
1.) anode 2.) cathode
The shorthand notation for an electrochemical cell is: anode electrode | 1.) anode solution || cathode solution | cathode 2.) electrode.
1.) anode 2.) electrode
The electrical potential (voltage)- E0cell of an electrochemical cell equals the difference between the E0 of its 1.) cathode and the E0 of its 2.) anode.
1.) cathode 2.) anode
The shorthand notation for an electrochemical cell takes into account the composition of the _______ , __________ , and the identities of the ions that are transferred
1.) cathode 2.) anode
Electric current will move only from an anode of 1.) higher electrical potential to a cathode with 2.) lower electrical potential.
1.) higher 2.) lower
If an electric current is applied between some substances, 1.) oxidation and, 2.) reduction will happen.
1.) oxidation 2.) reduction
The oxidation component of a redox reaction is called a(n) 1.) oxidation half-reaction; the reduction component of a redox reaction is called a(n) 2.) reduction half-reaction.
1.) oxidation 2.) reduction
When you place a strip of copper in an electrolyte solution of zinc sulfate, ________, ____________, and, ___________ occur simultaneously.
1.) oxidation 2.) reduction 3.) ion exchange
__________ is the process in which an atom or ion experiences an increase in its oxidation state.
Oxidation
An alkaline cell lasts longer than a zinc-carbon cell of the same size because there is a greater amount of _________ material.
anode
Oxidation takes place at the _________ of a zinc-carbon cell or general-purpose battery.
anode
The substance with the lower E0 will oxidize, so it will function as the _______.
anode
Classify: Cu→Cu2++ 2e-
anode; oxidation
Classify: Zn→Zn2++ 2e-
anode; oxidation
Although not technically correct, a voltaic cell is commonly known as a(n) _______.
battery
Reduction takes place at the carbon rod or _________ of a zinc-carbon cell or general-purpose battery.
cathode
As zinc atoms oxidize in a zinc-carbon cell, they lose electrons that travel through the electrical circuit and back to the _________.
cathode (carbon rod)
Classify: 2Ag++2e-→2Ag
cathode; reduction
Classify: Mn4++e-→Mn3+
cathode; reduction
The process in which a substance acts as both an oxidizing agent and a reducing agent and a reducing agent in the same reaction is called _______.
disproportionation
When a substance being oxidized in a redox reaction is connected by a conductor to a substance that is being reduced, a(n) ______ current will flow through the conductor.
electric
A device that converts chemical energy to electrical energy or uses electrical energy to cause a chemical reaction is called a(n) ____________________ cell.
electrochemical
The paste in between the anode and cathode in a zinc-carbon cell or general-purpose battery functions as a(n) _________.
electrolyte
What are three methods for balancing redox equations?
electron-transfer inspection ion-electron
An electrochemical cell that produces an electric current by oxidation of a fuel is called a(n) ______________ cell.
fuel
A disadvantage of fuel cells is that:
hydrogen is very explosive
The cathode in an alkaline cell is composed of _________.
manganese dioxide
A recharger applies electric current to the cell in the ________ direction of the operational electron flow.
opposite
Oxidation takes place when an atom or ion loses one or more electrons, thereby experiencing an increase in its _______ state.
oxidation
Reduction takes place when an atom or ion gains one or more electrons, thereby experiencing a decrease in its ________ state.
oxidation
Any chemical process in which an atom or ion experiences an increase in oxidation state is accompanied by a simultaneous decrease in oxidation state by another atom or ion, is a(n) ____________________.
oxidation-reduction reaction
A half-cell will reduce only if it is connected to a half-cell that ___________.
oxidizes
When a(n) _________ agent reduces, it causes oxidation in another substance.
oxidizing
The region where a chemical reaction occurs when two substances of different states, such as a solid and a liquid, come in contact is called ________ interface.
reaction
When a(n) _________ agent oxidizes, it causes reduction in another substance.
reducing
The double line in the shorthand notation indicates a(n) _________ bridge.
salt
A moist paper spacer separating the zinc anode from the electrolyte paste in a zinc carbon cell functions as a(n) _________.
salt bridge
An unbalanced chemical equation that includes the chemical formulas of the atoms, molecules, and ions in the reaction without coefficients, charges, or oxidation numbers is called a ____ equation.
skeleton
Ions that are present in an oxidation-reduction reaction but do not participate in oxidation or reduction are called _________ ions.
spectator
A reference hydrogen electrode with its reduction potential set to zero that is used to determine the reduction potentials of all other half cells is called a(n) __________.
standard hydrogen electrode
The oxidation component of a redox reaction is __________.
the oxidation half-reaction
The reduction component of a redox reaction is __________.
the reduction half-reaction
The biggest advantage of fuel cells is that:
they don't produce polluting emissions
A(n) _____________ cell is an electrochemical cell that uses a spontaneous redox reaction to convert chemical energy into electrical energy.
voltaic
1.) is produced at the anode interface when H+ ions react with OH- ions 2.) formed when a catalyst in one chamber causes H2 molecules to oxidize 3.) gas that is pumped into another chamber functioning as the cathode that produces OH- ions 4.) flow caused when the anode and cathode are joined with a conductor
water hydrogen oxygen electric current
Lab: Oxidation and Reduction Reaction
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Lesson 1 - Oxidation-Reduction Reactions
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Lab: Net Ionic Equations
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Lesson 2 - Balancing Redox Reactions
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Lesson 3 - Electrochemical Cells
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Lesson 4 - Electrode Potential
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The symbol E0 stands for ___________.
✘ electrical potential
Given: Cu2+ | Cu+ and Pt2+ | Pt What is the E0cell?
+1.03 V
Given: Mn2+ | Mn+ and Cu2+ | Cu What is the E0cell?
+1.53 V
Given: Ga3+ | Ga and Au3+ | Au What is the E0cell?
+2.05 V
Given: Co3+ | Co2+ and Ni2+ | Ni What is the E0cell?
+2.18 V
Given: F2 | F- and Cu2+ | Cu What is the E0cell?
+2.53 V
Determine if the following reaction is a redox reaction; if it is, select the correct overall oxidation -reduction reaction. P4O10(s) + 6H2O(l) →4H3PO4(aq)
+5 -2 +1 -2 +1 +5 -2 Yes, P4O10(s) + H2O(l) → 4H3PO4(aq)
Determine if the following reaction is a redox reaction; if it is, select the correct overall oxidation -reduction reaction. Pb(s) + FeSO4(aq) → PbSO4(aq) + Fe(s)
0 +2 +2 0 Yes, Pb + Fe2+ → Pb2+ + Fe
Determine if the following reaction is a redox reaction; if it is, select the correct overall oxidation-reduction reaction. 2Al(s) + Cr2O3(aq) → Al2O3(aq) + 2Cr(s)
0 +3 +3 0 Yes, 2Al + Cr2 → Al2 + 2Cr
Determine if the following reaction is a redox reaction; if it is, select the correct overall oxidation -reduction reaction. C(s) + O2(g)→ CO2(g)
0 0 +4 0 Yes, C + O2 → C + O2
Determine if the following reaction is a redox reaction; if it is, select the correct overall oxidation-reduction reaction. N2(g) + 3H2(g) → 2NH3(g)
0 0 -3 +1 Yes, N2 + 3H2 → 2N + 2H3
1.) 3CuCl2(aq)+2Al(s)→2AlCl3(aq)+3Cu(s) 2.) Cu(s)+2Ag+(aq)→Cu2+(aq)+2Ag(s)
1.) Reducing Agent: Al Oxidizing Agent: Cu Reduced: Cu Oxidized: Al 2.) Reducing Agent: Cu Oxidizing Agent: Ag Reduced: Ag Oxidized: Cu
1.) Zn(s) + CuSO4 (aq)→ZnSO4(aq) +Cu(s) 2.) Pb(s) + CuSO4 (aq)→PbSO4(aq) +Cu(s) 3.) Cu(s) + CuSO4 (aq)→NR
1.) Evidence of a Chemical Reaction: the layer of copper on metal zinc Substance Oxidized: zinc Substance Reduced: copper 2.) Evidence of a Chemical Reaction: the layer of copper on the lead Substance Oxidized: lead Substance Reduced: copper 3.) Evidence of a Chemical Reaction: nothing Substance Oxidized: none Substance Reduced: none
1.) Oxidation is a loss of electrons and 2.) reduction is a gain of electrons then students would know that the order matters.
1.) Oxidation 2.) reduction
A standard hydrogen electrode will function as a(n) _________ or a(n)_________, depending on the half-cell it is connected to.
1.) anode 2.) cathode
Use the electron-transfer method to balance this equation: Aluminum metal reacts with hydrochloric acid to produce aluminum III chloride and hydrogen gas.
2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g)
The oxidation half-reaction for a PEM fuel cell is:
2H2→ 4H+ + 4e-
The reduction half-reaction for a PEM fuel cell is:
2O2 + 4H+ + 4e-→ 2H20
Use the electron-transfer method to balance this equation: Solid antimony reacts with sulfuric acid to produce antimony(III) sulfate, sulfur dioxide and water, The chemical formula for antimony (III) sulfate is Sb2(SO4)3.
2Sb(s) + 6H2SO4(aq) → Sb2(SO4)3(aq) + 3SO2(g) + 6H2O(l)
Balance the equation using the ion-electron method. Aqueous sodium stannite reacts with solid bismuth(III) hydroxide to produce bismuth metal, aqueous sodium stannate, and water. The solution is basic.
3Na2SnO2 +2Bi(OH-)3 → 2Bi+3Na2SnO32-+3H2O
In the ion-electron method for balancing redox equations you follow the following steps:
Adjust the numbers of electrons and the coefficients in the half reactions to balance the mass and charge of both half reactions. Determine which atoms or ions have been oxidized/reduced and write out their oxidation and reduction half reactions. Cancel anything that appears on both sides of the equations after it has been balanced and combine the half-reactions to form the compounds in the skeleton equations. Rewrite the equation as an ionic equation, eliminate all molecule or ions that do not contain elements that were oxidized or reduced. If necessary, use inspection to adjust the coefficients of atoms or ions that did not undergo oxidation or reduction. Write out the skeleton equation.
In the electron-transfer method for balancing redox equations you follow the following steps:
Adjust the numbers of electrons and the coefficients in the half reactions to balance the mass and charge of both half reactions. Determine which atoms or ions have been oxidized/reduced and write out their oxidation and reduction half reactions. Insert the necessary coefficients into the skeleton equation. If necessary, use inspection. Write out the skeleton equation and assign oxidation numbers to all atoms and ions in the equation.
Given: F2 | F- and Cu2+ | Cu
Anode: a Cu2+ Cathode: b F2
Given: Cu2+ | Cu+ and Pt2+ | Pt
Anode: b Cu2+ Cathode: a Pt2+
Given: Ga3+ | Ga and Au3+ | Au
Anode: c Ga3+ Cathode: b Au3+
Given: Mn2+ | Mn and Cu2+ | Cu
Anode: c Mn2+ Cathode: d Cu2+
Given: Co3+ | Co2+ and Ni2+ | Ni
Anode: c Ni2+ Cathode: e Co3+
Why did the color change in the first experiment's solution?
Because the color of the solution starts to change to green as the aluminum ions are entering the solution and the aluminum is being oxidized (losing electrons). Simultaneously, the copper is being reduced (gaining electrons).
Why did the color change in the second experiment's solution?
Because within a few minutes, solid silver forms on the metal surface and copper ions enter the solution, giving the solution a bluish hue.
Classify between primary and secondary voltaic cells: disposable rechargeable reversible redox reactions nonreversible redox reactions must be charged before first used zinc-carbon cell, lithium cell, silver-oxides cell
Classify between primary and secondary voltaic cells: primary secondary secondary primary secondary primary
_____________ is the measure of the amount of electric current that can be generated by a voltaic cell to do work.
Electrical potential
_____________ is thought of in terms of reduction potential.
Electrical potential
________ is the branch of chemistry that deals with oxidation and reduction reactions that generate electricity and with chemical changes caused by electricity.
Electrochemistry
What are the net ionic equations for experiments one and two? a. Cu(s) + 3Ag+(aq) → Cu2+(aq) + 3Ag(s) b. Cu(s) + 2Ag+(aq) → Cu2+(aq) + 2Ag(s) c. 2Cu(s) + Ag+(aq) → 2Cu2+(aq) + Ag(s) d. 2Cu2+(aq)+3Al(s) →3Al3+(aq)+2Cu(s) e. 3Cu2+(aq)+2Al(s) → 2Al3+(aq)+3Cu(s)
Experiment 1: e Experiment 2: b
What happens during a redox reaction?
In a redox reaction, one of the compounds will be the reducing agent and the other one will be the oxidized. Both compounds will gain electrons resulting in the flow of electrons (electricity).
__________ is the process in which an atom or ion experiences a decrease in oxidation state.
Reduction
______________ is the tendency of a half-reaction to occur as a reduction half-reaction in an electrochemical cell.
Reduction potential
Use Table B-18 to predict whether the reactants in the following problems would produce the products shown. 2NH4Cl(g) + I2(g) → 2NH4I(g) + Cl2(g)
[Answer unknown] ANSWER IS NOT: ---Can happen either way as they are at the same level on the table. ---Yes, I2 will oxidize the Cl- as I2 is higher than Cl-. Redox should happen.
_______ is the measure of the difference in electrical potential between two points in a circuit.
Voltage
Use Table B-18 to predict whether the reactants in the following problems would produce the products shown in a redox reaction. 2Al(s) + 3H2SO4(aq) → Al2(SO4)3(aq) + 3H2(g)
Yes, Al will reduce the H+1 as H+1 is higher than Al. Redox should happen.
Use Table B-18 to predict whether the reactants in the following problems would produce the products shown. Zn(s) + FeSO4(aq) → ZnSo4(aq) + Fe(s)
Yes, Fe2+ will oxidize the Zn as Fe2+ is higher than Zn. Redox should happen.
Use Table B-18 to predict whether the reactants in the following problems would produce the products shown. LiNO3(aq) + Ag(s) → AgNO3(aq) + Li(s)
[Answer unknown] ANSWER IS NOT: ---Can happen either way as they are at the same level on the table. ---Yes, Li+ will oxidize the Ag as Li+ is higher than Ag. Redox should happen.
