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65 Cards in this Set
- Front
- Back
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Activation energy |
amount of energy needed to start a reaction |
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properties of useful fuels |
useful fuels must burn at a rate that is neither too fast nor too slow & have reasonable activation energy |
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sources of energy |
electric power, transportation, industry, residential and commercial |
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formation of fossil fuels |
forms thru photosynthesis by plants - plant matter digested by humans - plants also die and decay w/out oxygen and then covered w. sediment and compressed - coal and oil deposits form |
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coal - advantages |
-very large supply -coal reserves 20-40 times greater than oil reserves -can be cleaned by washing to remove sulfur or wet scrubbing to remove SO2 -can make polymers, gasoline, and cleaner burning fuels |
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coal - disadvantages |
-difficult to obtain (underground and strip mining) -solid and hard to transport -dirty fuel - produces CO2 and SO2 plus radioactivity upon burning |
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petroleum - advantages |
-liquid (easier to transport, pumped, pipelines) -gives more energy when burned -burns cleaner -still CO2 though |
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petroleum - disadvantages |
-much smaller supply -heavy reliance on imports -must be refined before use |
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Refining petroleum/fractional distillation |
-petroleum is a mix of hydrocarbons -mix separated into groups of compounds according to boiling point -liquid petroleum is heated & converted to gas -gases enter distillation column and rise -column is hottest at bottom and coolest at top -higher MW compounds condense back to liquids at bottom of tower -lower MW compounds continue up tower and condense farther up tower |
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cracking of petroleum |
higher molecular weight compounds broken down into lower MW compounds to make gasoline |
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natural gas - advantages |
-burns more cleanly and completely than other fossil fuels -produces 30% less CO2 than oil and 43% less CO2 than coal -transported by pipeline |
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converting fuels to electricity |
-when fuel is burned, bonds break and reform releasing energy -heat causes water to boil and form steam that drives a turbine -turbine rotates a coil of wire in magnetic field that generates electrons |
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substitutes for fossil fuels |
-fuels made from plants (biomass) -garbage -biogas -hydroelectric power -solar power -wind power -tidal power -geothermal power -oil sand -nuclear fission -hydrogen?? -fusion?? |
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Biomass |
ADV: -renewable and home grown DISADV: -less efficient than gas per gallon -costs more -much energy required to produce ethanol -lands set aside removed from food production -cannot produce enough ethanol to meet energy needs & still produce enough food -combustion produces CO2 |
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Garbage |
ADV: -burning garbage helps solve landfill problem -can control air pollution using same methods as coal-fired plants -can recover and recycle metals from garbage DISADV: -produces CO2 |
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Biogas |
ADV/DISADV: -works well on small scale DISADV: -produces CO2 |
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Hydroelectric power |
DISADV: -most good sites already used -damaging to river and fish habitats |
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Solar power |
DISADV: -works only in daylight -works best in sunny climates only -very land-intensive on large scale -problems w/ storage of energy -very dirty to make panels -heavily subsidized |
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Wind power |
DISADV: -works only when wind is blowing -occupies large amount of land -interferes w/ birds -problems w/ storage of energy -turbines require large amts of metals -heavily subsidized |
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Tidal power |
DISADV: -limited # of sites |
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Geothermal power |
DISADV: -must be near hot springs -waste water salty and must be treated -eventually depleted |
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Oil sand |
DISADV: -extraction difficult, expensive, devastating to environment -combustion produces CO2 |
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Nuclear fission |
DISADV: -the uranium must be mined -produces radioactive waste ADV: -doesn't produce CO2 |
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Hydrogen?? |
possibility |
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Fusion?? |
possibility |
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Individual uses of water |
-cooking and drinking -laundry -toilet -shower -faucets |
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overall water use by sector |
-Industrial mining: 5.4% -Power: 49% -Agriculture: 33.9% -Municipal/Household: 11.7% |
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properties of water |
-high boiling point -high melting point -most substances w/ low MW gases at room temp -H2O expands on freezing -solid water (ice) less dense than liquid water |
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Electronegativity |
measure of ability of an atom to attract e- shared in a covalent bond -atom w. high EN pulls on shared e- more strongly & pulls e- toward itself -EN decreases as you go down and left on periodic table -greater diff in EN between 2 atoms makes bond more polar |
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Polarity |
-greater diff in EN between 2 atoms makes bond more polar -even if a bond is polar, molecule containing that bond may be nonpolar overall -if central atom has no unshared pairs and all outer atoms are identical, molecule will be nonpolar -if there is an unshared pair of electrons on one side of central atom but not other, molecule will be polar -if outer atoms have diff EN molecule may or may not be polar depending on symmetry |
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Hydrogen bonding |
attraction between molecules -H bonds form when H attached to much more EN atom that has unshared e- |
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properties of water (cont.)/ |
-solid water less dense than liquid H2O -ice floats and expands on freezing. As H2O freezes, H bonds force H2O molecules into reg. lattice arrangement w/ lots open space. Upon melting, H2O molecules fill in those channels making liquid H2O more dense -cells die when they freeze bc expansion bursts cell walls -pipes burst when H2O freezes -H2O has high specific heat -Basically: it takes a lot of energy to heat H2O compared to other materials |
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Phase changes |
H2O (solid) + heat = H2O liquid H2O liquid + heat = H2O gas |
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Electrolytes |
form ions in solution and conduct electricity (soluble ionic compounds) |
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Nonelectrolytes |
do not form ions in solution and do not conduct electricity (soluble covalent compounds) |
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sources of water |
70% of surface of Earth covered with H2O -97.4% saltwater -2.24% frozen in ice caps -0.35% underground -0.01% lakes and rivers |
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The Water Cycle |
1. H2O evaporates from land and sea 2. H2O vapor condenses in clouds and returns to Earth as rain and snow 3. Rain and snow fill streams and lakes and filter underground |
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Water contamination |
clean water is a problem of 25% of world pop -80% of all sickness linked to contaminated H2O |
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W.C. - biological |
-raw sewage -pharmaceuticals |
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W.C. - chemical |
-agriculture like fertilizers and pesticides -industrial like chemicals and heated H2O -chemical more of a problem than biological |
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Safe Water Drinking Act |
contaminants regulated and EPA sets safe limits |
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MCLG |
level at which a person weighing 154 lb could drink 2 liters of H2O per day for 70 years |
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MCL |
legal allowable limit for contaminant safe limit w/ margin of safety |
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Municipal Drinking Water Treatment: Primary treatment |
-lowest level of treatment -large solids removed by screens -aluminum sulfate and calcium hydroxide added to remove small particles -H2O then passed thru charcoal, sand or gravel filters to remove more solids |
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MDWT: secondary treatment |
-bacteria killed w. chlorine compounds, ozone, or UV light |
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ammonium |
NH4+ |
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Acetate |
CH3COO- |
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Bicarbonate |
HCO3- |
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Cyanide |
CN- |
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Hydroxide |
OH- |
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hypochlorite |
OCl- |
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nitrate |
NO3- |
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Nitrite |
NO2- |
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Carbonate |
CO3(2-) |
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Sulfate |
SO4(2-) |
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Sulfite |
SO3(2-) |
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Phosphate |
PO4(3-) |
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alkali metals and ammonium |
soluble |
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nitrates and acetates |
soluble |
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chlorides - EXCEPTION!!: AgCl, Hg2Cl2, and PbCl2 |
soluble |
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sulfates - EXCEPTION!!: SrSO4, BaSO4, PbSO4 |
soluble |
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carbonates except alkali metals or ammonium |
insoluble |
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cyanides except alkali metals or ammonium |
insoluble |
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hydroxides and oxides except alkali metals or ammonium |
insoluble |
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sulfides except alkali metals or ammonium |
insoluble |
