Which is not a redox reaction?
|A)||CH4(g) + 2 O2(g) →CO2(g) + 2 H2O (l)|
|B)||4 Al4(s) + 3 O2(g) → 6 H2O(l) + 4 Al(OH)3(s)|
|C)||Zn(s) + 2 MnO2(s) + H2O (l) → Zn(OH)2(s) + Mn2O3(s)|
|D)||HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)|
As the lithium-iodide cell, Li + 1/2 I2 → LiI, discharges, lithium is oxidized and iodine is reduced. Which is the correct oxidation half-reaction?
|A)||Li + e– → Li+|
|B)||Li+ → Li + e–|
|C)||Li → Li+ + e–|
|D)||Li+ + e– → Li|
H2O2 can decompose into O2 and water. In this reaction
|A)||hydrogen is reduced and oxygen is oxidized.|
|B)||hydrogen is oxidized and oxygen is reduced.|
|C)||hydrogen is both oxidized and reduced.|
|D)||oxygen is both oxidized and reduced.|
|E)||no species is oxidized or reduced.|
This is a schematic of a typical dry cell. What is the reduction half-reaction in this cell?
|A)||Zn(s) + 2 OH– → Zn(OH)2(s) + 2 e–|
|B)||Zn(s) + 2 MnO2(s) + 2 e– → Mn2O3(s) + 2 OH–(aq)|
|C)||Zn(s) + H2O(l) + 2 MnO2(s) → Mn2O3(s) + Zn(OH)2(s)|
|D)||2 MnO2(s) + H2O(l) 2 e– → Mn2O3(s) + 2 OH–(aq)|
In an electrochemical cell, electrons flow
|A)||from the cathode to the anode.|
|B)||from the anode to the cathode.|
|C)||through the salt bridge.|
|D)||right to left.|
A device in which electrical energy is used to perform a chemical transformation is called
|A)||an electrochemical cell.|
|B)||an electrolytic cell.|
|C)||a hydroelectric cell.|
|D)||a hydrogen cell.|
In what commercial application is this reaction used?
PbO2(s) + Pb(s) + 2 H2SO4(aq) → 2 PbSO4(s) + 2 H2O (aq)
|A)||alkaline cells used in calculators|
|B)||solar cells at remote power stations|
|C)||storage battery in most automobiles|
|D)||photovoltaic cells for direct conversion of sunlight|
Which type of battery or cell would likely be used in this portable drill?
|A)||a mercury oxide button battery|
|B)||a lead storage battery|
|C)||a nickel-cadmium battery|
|D)||a hydrogen-oxygen fuel cell|
What condition must be met for a battery to be rechargeable?
|A)||Either the anode or the cathode must generate a gas as a result of the electrochemical reaction.|
|B)||The battery must generate electricity using an acid-base reaction rather than using an oxidation-reduction reaction.|
|C)||The battery must be open to the outside so that internal pressure will not build up.|
|D)||The electrochemical reaction of the battery must be reversible.|
The term hybrid most commonly describes a car containing
|A)||two different types of batteries.|
|B)||both a battery and a conventional gasoline-powered engine.|
|C)||both a conventional gasoline-powered engine and an ethanol-powered engine.|
|D)||a battery and a hydrogen-oxygen fuel cell.|
What does this Honda FCX car use to generate power?
|A)||lead-acid storage batteries|
|B)||hydrogen fuel cells|
A major advantage of a fuel cell over a lead-acid battery is that a fuel cell
|A)||will not run down like a battery as long as fuel and oxygen are supplied.|
|B)||generates electricity without the need for an oxidation-reduction reaction.|
|C)||is 100% efficient at generating electricity, but a battery is less than 1% efficient.|
|D)||produces more fuel than it consumes.|
Which are applications of metal hydrides?
|A)||photovoltaic devices and hydrogen storage materials|
|B)||hydrogen storage materials and electrodes for rechargeable batteries|
|C)||electrodes for rechargeable batteries and photovoltaic devices|
|D)||photovoltaic devices and reforming catalysts|
Compared to PEM fuel cell, solid oxide fuel cells (SOFCs) operate at a ________ temperature and are _____________ efficient.
Which is NOT an advantage of using hydrogen as a fuel as compared to fossil fuels?
|A)||Combustion products are less harmful to the environment.|
|B)||With current technology, H2 is a renewable resource.|
|C)||Hydrogen has about 3 times the energy content per gram compared to the best fossil fuels.|
|D)||Hydrogen gas has very few of the impurities responsible for the production of acid rain.|
Which is not a problem with moving towards a hydrogen-energy based economy?
|A)||finding raw materials containing hydrogen|
|B)||separating hydrogen from raw materials|
|C)||storing hydrogen safely|
|D)||transporting hydrogen economically|
Hydrogen gas can be made by reacting steam with methane, producing H2 and CO2. Which statement about this process is true?
|A)||The reaction is exothermic and needs improved catalysts to increase the yield.|
|B)||The reaction is endothermic and must be carried out at high temperatures.|
|C)||The reaction must be carried out using the process of electrolysis, which requires energy.|
|D)||The products are unstable often resulting in an explosion.|
Which statement about hydrogen is false ?
|A)||Hydrogen has a high energy density (kJ/g).|
|B)||Virtually no hydrogen is present in the Earth's atmosphere because large quantities are consumed by the sun.|
|C)||It takes a significant amount of energy to separate hydrogen from water.|
|D)||There are abundant natural sources of hydrogen in forms other than H2(g).|
19. Which are advantages of using photovoltaic cells to convert sunlight directly into electricity over using more conventional methods?
I non-polluting in operation
II low maintenance during operation
III modular, so any size PV array can be constructed
IV large amount of space needed for a photovoltaic array
V quiet while in operation
VI high cost of producing the PV cells
|A)||I, II, IV, and V|
|B)||I, II, III, and V|
|C)||III, IV, and VI|
|D)||III, IV, V, and VI|
What type of semi-conductor is shown in this diagram?
Note: The smaller filled circles represent electrons. The larger filled circles represent Si atoms. The patterned circle represents a doping atom.
|A)||a gallium-doped p-type silicon semi-conductor|
|B)||a gallium-doped n-type silicon semi-conductor|
|C)||an arsenic-doped p-type silicon semi-conductor|
|D)||an arsenic-doped n-type silicon semi-conductor|