Chm chapter 8 & 9
proteins have _______ PET has __________ amides _________ esters ___________
20 different monomers, 2 different monomers, link protein monomers together, and link PET monomers together
half reaction reduction example
2H+ + 2 e- --> H2
hydrogen gas can be converted into methane
CH4 + 2 H2O + heat --> 4 H2 + CO2
which of the following pollutants are released into the environment during the production or incorrect disposal of batteries.
CO2, toxic metals, SO2
key features of a fuel cell
H2 passes through PEM and is oxidized to form two H+ ions, solid polymer electrolyte materials separate the reactants, the anode in a fuel cell simply acts as a conductor and does not participate in the oxidation reaction
whoch of the following products are formed during the electrosis of water?
H2, O2
H2 burns to form _________, CH4 burns to form _________, the energy from H2 combustion _________________, the energy from CH4 combustion ___________________.
H2O only, CO2 and H20, is higher than (124.5 kj/g), is lower than (50 kJ/g)
HDPE vs. LDPE
HDPE- stronger, more ordered structure, higher melting point, greater rigidity, opaque. LDPE- transparent, stretchy, irregular tangle of polymer chains, less strength, lower melting point
describe Group 1A metals
Li is lighter than Na; Li, Na, and K are highly reactive metals; Na and K are more abundant than Li in Earth's crust
correctly describe the role of metal hydrides for the storgae and transportation of hydrogen gas
Metal hydrides are selective and can seperate H2 from larger molecules such as O2, CO, and CO2. When placesd under high pressure the metal hydride acts like a sponge to absorb H2 molecules
common galvanic cells in order of increasing voltage, least powerful at the top.
Ni-Cd, alkaline, lead-acid, lithium-ion
advantages of PHEV's as compared to gas cars
PHEV's are less expensive to operate per mile basis, the electric energy provided by the battery decreases the direct emissions from the tailpipe
formed through addition polymerization
PP, HDPE, LDPE, PS, PVCX
discharging
Pb and Pb2 are converted into PbSO4-
recharging
PbSO4 is converted to Pb and PbO2
T/F recycling a synthetic polymer can be more energetically costly than making a new one
T
H2 is the fuel in _______ Hydrocarbon fuel cells are used in ___________________ A combustion engine produces __________________ A hydrogen fuel cell produces _______________
a hydrogen fuel cell; a combustion engine; CO, CO2, H2, and energy; H20 and electricity
n-type semiconductor
abundance of electrons, replacing Si atom with As
environmental consequences of making batteries
acid rain produced as a result of SO2 release during the metal ore refining process, lead-acid batteries may leak and release corrosive material into the evironment, and the mining of metal ores leaves mine tailings and other waster that must be cleaned up
chasllanges associated with the fabrification of photovoatic devices
although silicon is abundant, it does not occur in its elemental form, some radiant energy is lost due to reflection and absorption (to produce heat instead of electric current)
half-reaction charateristics
always occur in pairs. include electrons. electrons either show up on the left side or he right side of the half-reaction, never both.
thin-film solar cells are made from _________ silicon or nonsilicon materials such as ________
amorphous, CdTe
in both fuel cells and conventional batteries
an electrochemical reaction produces energy
lead acid ________, alkaline _________, lithium-ionide ________, nickel-metal hybrid (NiMH) __________.
automobile batteries, flashlights and small appliances, pacemakers, and hybrid vehicle batteries
hybrid electrical vehicle (HEV) is propelled by
both a conventional gasoline engine and an electric motor run on batteries
photovoltaic cells power
calculators, communication satellites, saftey lighting, and navigational bouys
thermoplastic polymer
can be melted and reshaped with heat
voltage of a battery affected by
chemical composition, number of electrochemical cells wired together
half-reaction
chemical equation that shows the electrons either lost or gained by the reactants
reduction
chemical species gains electrons. electrons show up on the left side.
oxidation
chemical species loses electrons. electrons show up on right side.
CSP
concentrating solar power ,solar collectors gater a large area of sunlight into a smaller area. The light is converted to heat ehich is used to generate electricity
solar cell/photovoltalc cell
convert light directly into electrical energy
fuel cell
converts the chemical energy of a fuel directly into elecricity without burning the fuel
sources for materials for renewable polymers
cotton, wood, starch
electrolsis
decomposition of water into H2 and O2 by passing electric curent through it
p-type semiconductor
deficit of electrons. Boron and Gallium may funstion as, replace Si with Ga
desireable for consumers about batteries
ease of recycling, affordability, long lifetime
electrodes
electrical conductors within a cell that serve as sites for chemical reactions
electrolytic cell converts
electrical energy into chemical energy
thw flow of electrons through an external circuit produces ____________, which is the flow of electrons from one region to another driven by a difference in ______ energy.
electricity; potnetial
galvanic cell
electrochemical cell that converts the energy released into a spontaneous chemical reaction into electrical energy. Several wired together makes up a true battery
describe the operation of a photoelectrochemical cell which cold potentially harness the sun's energy to produce H2?
electrons arrive at the cathode where they reduce H+ ions to H2, the cathode is made of Pt metal, dye particles at the anode absorb light causing their electrons to move to higher energy states
electrodes
energy conductors within a cell that serve as sites for chemical reactions, facilitate this electron transfer.
main disadvantage in using hydrogen as a fuel source is its
flammability
electricity
flow of electrons from one region to another that is driven by a difference in potential energy
dispersion forces
forces a result of an attraction between molecules due to a distortion in the electron cloud, uneven distribution of negative charge
standard flashlight battery
galvanic cell
energy harnessed by drilling into underground resoviours containing hot water or steam
geothermal
H2 gas can be stored using metal ___________ such as LiK, which absorb H2 molecules into the spaces within their crystal structure
hydrides
which is stronger?
intra = covalent, stronger; inter = individual molecules, weaker
cell voltage
it is a function of the chemicals used to construct the battery, higher voltages are possible by connecting cells
relationship between molecular shape and strength of dispersion forces
large surface area have more points of contact and therefore experience stronger dispersion forces
bad idea to dispose automobile batteries in landfills
leaching of chemicals from the batteries will eventually lead to groundwater contamination, toxic materials such as PbO2 will be able to enter the environment, and these metals become too widely dispersed to efficicntly collect for reuse
a hydrogen fuel cell produces energy ______ rapidly an with _____________ efficiency than the production of energy in a conventional combustion engine.
less, higher
hydrogen-rich fuels
liquid hydrogen-rich fuels include methanol and ethanol, these fuels can be used to power fuel cell vehicles, which have an on board reformer, and these fuels are converted into H2 by a device that uses heat, pressure, and catalysts to run a chemical reaction
recycled-content products
materials that would have otherwise been found in a waste stream
proteins and nylon have in common
monomers of both polymers are linked through amide linkeges, both polymers are copolymers, both polymers are formed through condensation polymerization
noncrystalline silicon absorbs photons _________ effectively than crystalline silicon, allowing the construction of ________ semiconductor layers and cheaper photovoltaic cell.
more, thinner
an addition polymer is formed when two monomers containing ____ bonds react in the presence of a ____ initiator
multiple, radical
naturally occuring source of hydrogen gas
natural gas, water, methane
two types of batteries used in hybrid electric vehicles
nickle-metal hybride batter, and lead-acid storage battery
recyclable products
not necessarily made from recycled materials but can themselves be recycled
fuel cells are a form of distributed generation since they generate electricity
on site where it is used
voltage
once the electrical circuit is complete, the voltage can be measured across the cell. voltage is the difference in electrochemical potential between the two electrodes in a galvanic cell
HDPE examples
opaque containers, toys, fencing, heavy-duty pipes
anode
oxidation takes place and is the source of electrons in the energy flow
Ina fuel cell, h2 is _________ to form 2H+ as it passes through PEM. These H+ ions combine with o2 at the cathode in a ______ half-reaction to form H2O.
oxidized, reduction
in a fuel cell, H2 is ________ to form 2H+ as it passes through PEM. These H+ ions combine with O2 at the cathode in a ____________ half-reduction to form H20.
oxidized, reduction
which methos ia the most enviromentally friendly? nuclear burning fossil fuels, photovolaic cells
photovoltaic cells
LDPE examples
plastic milk bottles, grocery bags, plastic food wrap
moleculae made of many repeating units linked together is called a ________, while the repeat units are called _________.
polymer, monomers
post consumer content
previously used industrially or individually that would have otherwise been discarded
doping
process of adding small amounts of other elements to pure silicon
a battery that employs electrochemical reactions that run both ways is _______.
rechargeable
plug-in hybrid vehicle
rechargeable batteries fro short commutes to run an electric motor and switches to combustion for longer distances.
4 r's of solid waste processing
recycle, reuse, reduce, recover
advantages of recycling
reduces waste, prevents air, water, and soil pollution; conserves natural resources
cathode
reduction takes place, receives electrons through anode through an external circuit to complete the reduction.
hybrid cars
release fewer pollutants over lifetime of car, deliever better milage in city driving, and use less gasoline
half-reaction
shows the electrons lost by reactants in a galavantic cell, the overall process occuring in a galavantic cell includes both the oxidation and the reduction reaction. A half-reaction shows the electrons gained by the reactants in a galavantic cell
installation of solar panals to power homes
solar panals are usually due south, installation on a system that rotates to follow the sun's path has a higher initial cost than a fixed solar array fot eh same size, and instillation on a system that rotates optimizes efficiency of the unit.
what from this image is a synthetic polymer
tennis ball, running shoes, and tennis racket
which of the following describe the process occurring at the anode of a galvanic cell?
the anode is the source of electrons in the current flow, and oxidation takes place at the anode
lithium ion batteries are better than alkali metal batteries because
the are very light and ideal for portable applications, they typically provide higher voltages than other batteries
describe how a simple photovoltalic cell is assembled?
the conduction of electricity is made possible by p-n junctions, a specific arrangement of p-n junctions ensures that electrons flow in a specific direction, and multiple layers of doped n and p type are placed inclose contact
correctly describe the power system of a hybrid electric vehicle (HEV)?
the electric motor draws power from the nickle-metal hydride batteries to power he vehicle at low speeds, regenerative braking is used to charge battereies during braking and deceleration, and the nicle-metal engine assists the electric motor during normal driving
What describes electricity and its production by a galvantic cell?
the flow of electrons from one region to another is driven by differences in potential energy, electricity is produced by the movement of electrons through an external circiut
which may impact the cost (both economic and environmental) of a battery?
the metals in batteries are refined from ores and this requires energy, the incorrect disposal of "dead" batteries may result in hazardous chemicals entering the enviromnent, smeltering produces CO2
two main disadvantages of the production of hydrogen from methane (CH4)?
the process requires significant energy input, CO2 is produced in addition to hydrogen
current
the rate of electron flow in a cell, measured in amperes
photovoltaic cells constructed of thin layers of alternating n and p type semiconductors are preferable to those with thicker layers because
they are more efficient due to lower internal resistence, smaller quantities of silicon are needed for device construction
alkaline batteries are called that becasue
they operate in a basic medium
one way to generate H2 for fuel cells is by the decomposition of water. The most economical way of generating the heat required to decompose water is to
use a photoelectrochemical cell
a fuel cell _________, a conventional battery, the electrodes participate in reactions _______, and the electrodes simply serve as conductors _____________.
utilizes an external source of fuel and oxidant, regulate no external source of heat or oxidant, in a conventional battery, in a fuel cell
the difference in electrochemical potential between the two electrodes of an electrochemical cell is called the ________ of the cell, measured in _________.
voltage, volts
pre consumer content
waste remaining from the manufacturing process
NOT describe the capture of wind ebnergy (both in the past and present)
wind farms can be placed at any location in the world to produce energy
typical alkaline battery exploits reactions involving
zinc, magnese
