General Chemistry
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Using the given reduction potentials below, identify whether the reduction of Cl2(g) by HNO2(aq) will occur spontaneously at standard-state conditions.
E°red Cl2/Cl– = 1.358 VE°red NO3–/HNO2 = 0.934 V
Using the given reduction potentials below, identify whether the oxidation of Pt(s) by Zr4+(aq) will occur spontaneously at standard-state conditions.
E°red Pt2+/Pt = 1.18 VE°red Zr4+/Zr = –1.45 V
Using the given reduction potentials below, identify whether the reduction of Ag+(aq) by Cu+(aq) will occur spontaneously at standard-state conditions.
E°red Ag+/Ag = 0.800 VE°red Cu2+/Cu+ = 0.153 V
Due to an unexpected storm, the power in your resthouse has been knocked out. You want to know the latest news, but your tablet is dead. You want to create a battery to charge it. From the materials found in your resthouse, the following allows you to make a battery:
1.00 M Cu2+ solution from herbicide
1.00 M Zn2+ solution from calamine lotion
Salt bridge from filter paper soaked in a KNO3 solution derived from toothpaste
Calculate the voltage that can be generated.
A photographer was on a trip to an exotic place to capture stunning landscapes when the electrical system of his RV was knocked out. He tried to locate himself on the road using the maps app on his tablet but the tablet's battery was dead. In his RV, he found safety matches that he could use to make a 1.0 M KClO3 solution. He bought his RV from an old photographer, so he was able to find a small amount of silver nitrate (AgNO3) and made a 1.0 M solution. He was wearing a silver ring and had a $100 American Platinum Eagle coin in his pocket. He used a paper towel dipped in salt solution as a salt bridge.The battery in the tablet requires 5.0 V for charging. Can this battery charge his tablet?
An experiment is conducted on an alternative source for the production of methanol (CH3OH). One way to determine if methanol is produced is through titration with acidic potassium dichromate. The presence of methanol can be determined since Cr2O72− is converted to Cr3+ and indicated by a color change from orange to green. During titration, methanol is oxidized to formaldehyde (CH2O) as described in the following chemical reaction:
3CH3OH(aq) + Cr2O72−(aq) + 8H+(aq) → 3CH2O(aq) + 2Cr3+(aq) + 7H2O(l)
If the standard half-cell potential for the reduction of formaldehyde to methanol is 0.110 V, what is E° for the reaction?
During the weekend, you stayed in your vacation villa in the countryside when a blackout happened. You desire to create a battery to charge your phone. You brought a liquid foundation with you which can be used to make a 1.00 M Mg2+ solution. You have bathroom cleaners in your villa that can produce a 1.00 M H2O2 solution. You also made a salt bridge from tissue paper soaked in a KNO3 solution made from makeup primer.
Determine the voltage that can be produced. (E°red,Mg2+ = −2.37 V; E°red,H2O2 = 1.78 V)
Provide the balanced equation and calculate the value of E° for the formation of O2 and H2O from H2O2 given the following half-reactions and corresponding E° values:
H2O2(aq) + 2 H+(aq) + 2e− → 2 H2O(l) E°H2O2→H2O = 1.78 V
O2(g) + 2 H+(aq) + 2e− → H2O2(aq) E°O2→H2O2 = 0.70 V
Determine if the reaction is spontaneous under standard-state conditions.
Determine E° for the following reaction:
F2(g) + 2Na(s) → 2Na+(aq) + 2F−(aq)
Under standard-state conditions, is the reaction spontaneous?
Among the following spontaneous cell reactions,
Y+ + W → Y + W+
W+ + Z → W + Z+
Y+ + Z → Y + Z+
X+ + Z → X + Z+
Y+ + X → Y + X+
Identify the reaction that produces the highest voltage.
True or False. In the hydrogen fuel cell, the reaction of hydrogen gas with oxygen that produces water is spontaneous while the reverse reaction is not spontaneous.
True or False. The reduction of Co3+ to Co2+ by H2O2 can occur spontaneously in an acidic solution under standard conditions.
The overall reaction for a zinc-bromine battery is: Br2(l) + Zn(s) → 2 Br–(aq) + Zn2+(aq). Using the standard reduction potentials below, determine the standard emf generated by the battery.
Zn2+(aq) + 2 e– → Zn(s) E°red = –0.76 V
Br2(l) + 2 e– → 2 Br–(aq) E°red = +1.07 V
Everyday household items such as flashlights and radios use alkaline batteries. The overall reaction in the battery is as follows: Zn(s) + 2 MnO2(s) ⇌ ZnO(s) + Mn2O3(s). Using a reliable source, give the two half-reactions that occur in the battery and calculate the standard emf generated by the voltaic cell.
Consider the following half-reactions with their standard reduction potentials.
(a) Au+(aq) + e– → Au(s) E°red = 1.692 V(b) Cr2+(aq) + 2 e– → Cr(s) E°red = –0.913 V(c) Zn2+(aq) + 2 e– → Zn(s) E°red = –0.763 V(d) Bi3+(aq) + 3 e– → Bi(s) E°red = 0.308 V
Identify the combination of these half-cell reactions that will results in an overall reaction with the smallest positive E°cell, then provide the value of E°cell.
Determine the standard cell potential for the overall reaction: 6 HClO(aq) + 6 H+(aq) + 2 Au(s) → 3 Cl2(g) + 6 H2O(l) + 2 Au3+(aq).
2 HClO(aq) + 2 H+(aq) + 2 e– → Cl2(g) + 2 H2O(l) E°red = +1.63 V
Au3+(aq) + 3 e– → Au(s) E°red = +1.498 V
A certain voltaic cell has a standard cell potential of 2.516 V and is given by the following overall reaction: AuBr4–(aq) + Al(s) → Au(s) + 4 Br–(aq) + Al3+(aq). If the E°red of Al is –1.662 V, determine the E°red for the reaction associated with Au.
Which of the following images shows the correct electrolytic cell with labeled anode and cathode and indicated electron flow direction where Co is oxidized to Co2+ and Ni2+ is reduced to Ni? What are the half-reactions at the anode and the cathode? How much voltage is needed to run the reaction?
For the following electrochemical cell, calculate the standard cell potential:
MnO4–(aq) + 4 H+(aq) + 3 K(s) → MnO2(s) + 2 H2O(l) + 3 K+(aq)
For the following balanced redox reaction,
Pb2+(aq) + H2S(g) → Pb(s) + S(s) + 2H+(aq)
What is the E°cell? Is the forward direction of the redox reaction spontaneous or nonspontaneous?
Cr3+(aq) + Fe(s) → Cr(s) + Fe3+(aq)
Is the forward direction of the redox reaction spontaneous?
Ba2+(aq) + 2 Na(s) → Ba(s) + 2 Na+(aq)
Sn4+(aq) + Mg(s) → Sn2+(aq) + Mg2+ (aq)
Calculate the standard cell potential for the following reaction:
IO3- (aq) + 2 H+ (aq) + 2 Cl- (aq) → Cl2 (aq) + IO- (aq) + 2 H2O (l)
At 25°C, which of the following pairs would you predict to react spontaneously?
Ba2+(aq) + 2e- → Ba(s) E° = -2.90 V
Sn4+(aq) + 2e- → Sn2+(aq) E° = 0.15 V
Mg2+(aq) + 2e- → Mg(s) E° = -2.37 V
Zn2+(aq) + 2e- → Zn(s) E° = -0.73 V
Na+(aq) + e- → Na(s) E° = -2.71 V
Fe3+(aq) + 3e- → Fe(s) E° = -0.036 V
Cr3+(aq) + 3e- → Cr(s) E° = -0.73 V
Ni2+(aq) + 2e- → Ni(s) E° = -0.23 V
Nickel-iron batteries have less impact on the environment because nickel-iron batteries don't contain cadmium, which is considered a hazardous material. The overall cell reaction for a nickel-iron cell is:
2 NiO(OH)(s) + 2 H2O(l) + Fe(s) → 2 Ni(OH)2(s) + Fe(OH)2(s)
Which would be higher: the specific energy density of a nickel-iron battery or the specific energy density nickel-cadmium battery?
NiO(OH)(s) + H2O(l) + e− → Ni(OH)2(s) + OH−(aq) E°red = +0.49 VFe(OH)2(s) + 2 e− → Fe(s) + 2 OH−(aq) E°red = −0.88 VCd(OH)2(s) + 2 e− → Cd(s) + 2 OH−(aq) E°red = −0.81 V
Referring to the Standard Reduction Potential Table, predict whether the oxidation of Cu+(aq) by I2(s) will take place under standard-state conditions.