Energy: Hard Work & Hot Stuff
• Energy is the ability to do work.
• Work is done when movement occurs
against a restraining force, and it is equal to
the force multiplied by the distance over
which the motion occurs.
• Heat is that which flows from a warmer to a
cooler substance
• Temperature is a property that determines
the direction of heat flow. When two bodies
are in contact, heat always flows from the
object with a higher temperature to the one
with lower temperature.
Energy: Hard Work & Hot Stuff
• Heat is a consequence of motion at
the molecular level. When matter, for
example liquid water in a pan, absorbs
heat, its molecules move more rapidly.
• Temperature is a statistical measure of
the average speed of that motion.
Hence, temperature rises as the
amount of heat energy is a body
increases.
Energy: Hard Work & Hot Stuff
• Units of energy are termed the Joule (J).
• Calories are also used as a measure of
energy.
• 1cal = 4.184J
• 1Cal = 1kcal = 1000 cal
• 1Cal = 4184J
Your Turn
• Convert the 425 kcal released when a
donut is metabolized to joules. Then
calculate the number of books you
could lift to a shelf 6 feet off the floor
with that amount of energy. (It takes 1J
of energy to lift a book 4 inches.)
Your Turn
• A 12 oz can of a soft drink has an
energy equivalent of 92kcal. Assume
that you use this energy to lift concrete
blocks that weigh 22lb (10kg) each.
How many of these blocks could you
lift to a height of 4 feet with this
quantity of energy? (It takes 10J of
energy to lift a book 4 inches.)
Energy Conservation and
Consumption
• Strictly speaking, energy is not
consumed.
• Law of Conservation of Energy or the
First Law of Thermodynamics assures us
of this.
• The energy in the universe is constant.
• However, energy sources like coal, oil,
natural gas are consumed.
• The U.S. and Canada use more fossil
fuel than any nation at 95 million kcal.
Energy Conservation and
Consumption
• Graphs like on ICT show that the
world’s reliance and usage of fossil fuel
is growing exponentially.
• We are using 5 times as much fossil
fuels in 2000 than we did in the 1950’s.
• Our main sources of energy are oil,
natural gas, coal, nuclear power and
hydropower, geothermal, wind and
solar power in that order.
Consider This…
• Imagine that you are put in a time
machine and transported 200 years
into the future. You become an instant
celebrity. The talk show host of the day
invites you in to be interviewed. The
first question is “How could the people
of your century feel justified in using up
so much of the world’s store of nonrenewable resources such as oil and
coal? What is your answer?
Zero Talking on this Activity
• Get in groups of 3—2 min
• Give your essay to the person to the right for them
to read—10 sec
• Read the article that you now have and respond
to them in another short paragraph—2 min
• Pass your paper to the right again—10 sec
• Read the article and the response and write a
response of your own commenting on the original
and the response—2 min
• Give the paper back to the original author—2 min
• Read the responses to your essay—2 min
• Discuss your papers and responses with each
other—2 min
Energy: Where from and How
Much?
• At a time when the nation is seeking
new sources of energy, it is reasonable
to ask what is it that makes some
substances such as coal, oil or wood
usable as fuels, while many others are
not.
• To find the answer, we must consider
the properties of fuels and the means
by which energy is released from
them.
Energy: Where from and How
Much?
• The most common energy-generating
chemical reaction is burning or
combustion.
• Combustion is the combination of the fuel
with oxygen to form CO2, H2O and energy.
• The stored energy (potential energy) of the
reactants is more than the stored energy
of the products, so the 1st Law of
Thermodynamics tells us that energy must
be given off (usually as heat).
Energy: Where from and How
Much?
CH4 + O2  CO2 + H2O + Energy
• The above reaction is exothermic.
• This means that energy was given off
as the reactants broke bonds and
reformed bonds to make products.
• Endothermic reactions are those that
need energy to be added to the
reactants in order to turn into
products.
Energy: Where from and How
Much?
• The amount of heat energy produced
by a reaction such as the previous can
be calculated using a calorimeter.
• The amount of heat generated
depends on the amount of fuel
burned.
• Heat of combustion is the quantity of
heat energy evolved when a specified
amount of a substance burns in
oxygen. (kJ/mole or equivalents)
Energy: Where from and How
Much?
• If the heat of combustion of methane
is determined by calorimetry to be 802
kJ/mole, it means that every mole of
methane emits 802kJ of energy.
• We can use factor label to determine
that the amount of energy given off
per gram is 52kJ/g.
• The fact that heat is evolved signals
that there is a decrease in the energy
of the chemical system during the
reaction.
Energy: Where from and How
Much?
• The fact that heat is evolved signals
that there is a decrease in the energy
of the chemical system during the
reaction.
• So, the energy change is reported
as -802kJ/mole.
Energy: Where from and How
Much?
• But where does the energy come
from? We have discussed that energy
is released during a reaction such as
this, and that the reactants have more
energy than the products, but where
does the energy come form?
• The answer is found in the molecular
structures of the compounds…
Today
• Pick up more notes at desk nearest door.
• WHAT!? MORE NOTES?!
• Yes, more notes…
• Get out a sheet of paper, periodic table,
pen/pencil, and a calculator for the graded quiz.
• QUIZ?!
• Yes, a graded quiz.
• GRADED QUIZ?! THIS STINKS!
Yes, I know.
Today’s Graded Quiz Check
Absolutely no talking or asking questions—if you are talking
you will get no credit for this graded quiz.
1. Define electronegativity (χ).
2. Which has a higher χ,
Ba or O
Cl or F
N or C
3. Draw NF3 and check the formal charges.
4. List two units to measure heat.
5. What does it mean to say the heat of
combustion of methane is -802kJ/mol?
Final Quiz Question
6. According to the information given to you,
the heat of combustion of methane is
802kJ/mole. Methane is usually sold by the
standard cubic foot (SCF). One SCF
contains 1.25moles of CH4. Calculate the
energy (in kJ) that would be released by
burning 15 SCF of methane. (Hint: this is a
factor label problem)
Energy: Where from and How Much?
Write the balanced equation for the combustion of methane (CH4).
Draw all the molecules from this equation.
O
H
H
C
H
H
+ O=O
 O=C=O +
H
O=O
H
O
H
H
• Bond breaking is endothermic—need
energy to tear away atoms.
• Bond forming is exothermic.
Energy: Where from and How
Much?
O
H
H
C
H
H
+ O=O
 O=C=O +
H
O=O
H
O
H
• For this reaction to take place, 4 C-H
bonds and 2 O=O bonds are broken
and 2 C=O and 4 O-H bonds are
formed.
H
Calculating Energy Changes in
Chemical Reactions
• Bond energy is the amount of energy
that must be absorbed to break a
specific chemical bond.
• The more bonds broken, the more
energy it takes.
• All values in the table are given in
kJ/mole and are given a positive sign.
• Energy used to break bonds is given
(+) and energy given off is given (-).
Calculating Energy Changes in
Chemical Reactions
•
•
•
•
Breaking Bonds (endo)
4 C-H bonds 411kJ =
1644kJ
2 O=O bonds 494kJ =
988kJ
Total energy absorbed 2632kJ
•
•
•
•
•
Making Bonds (exo)
2 C=O bonds -799kJ =
4 H-O bonds -459kJ =
Total energy released
Net energy
-1598kJ
-1836kJ
-3434kJ
-802kJ (released)
More Funner Way
ΔHºrxn = (Σ bonds broken) – (Σ bonds formed)
Heat of the
reaction at
standard
conditions
Sum of
You Try
• Determine the heat of combustion of one
mole of propane (C3H8).
• Acetone (H3CCOCH3) can be converted to
isopropyl alcohol (H3CHCOHCH3) by
reacting it with H2 gas. Calculate the heat
change of this reaction.
• Oxygen difluoride reacts with water to form
oxygen and hydrofluoric acid. If the ΔHºrxn is
-318kJ/mole, what is the bond dissociation
energy associated with an O—F bond?
• How much energy is given off when 150mL
of ethanol (C2H5OH) is burned on a desk?
(Density = 0.85g/mL)
You Try
• How much energy is given off when
100g of methane reacts with oxygen?
Hess’s Law
• Hess noticed that heat change was a state
function—which means…
• That it doesn’t matter the path you take to
get to the end as long as you get to the
end.
• A state function is like going to the baseball
field.
• There are many paths that you can take to
get to the field—but the displacement of
your body from this spot to the field is the
same.
Hess’s Law
BB
Field
U
Hess’s Law
• In all cases, you ended up about 500 feet
from where you started.
• Hess didn’t care about the path you took as
long as you ended up in the same place.
• He took this idea into the chemistry world.
• He stated: in going from a particular set of
reactants to a particular set of products, the
change in enthalpy (H) is the same whether
the reaction took place in one step or a
series of steps.
Hess’s Law
• N2(g) + 2O2(g) 2NO2(g)
ΔH1 = 68kJ
• This shows the reaction in one step.
• But the reaction can be thought of as
occurring in 2 distinct steps…
• N2(g) + O2(g)  2NO(g)
ΔH2 = 180kJ
• 2NO(g) + O2(g)  2NO2(g) ΔH3 = -112kJ
• N2(g) + 2O2(g) 2NO2(g)
ΔH1 = 68kJ
Hess’s Law
• Often we will know the ΔH of a
reaction or we can use calorimetry to
get it.
• But sometimes we are unable to use
any means to calculate it—other than
Hess’s Law.
Hess’s Law
• For example it is too difficult to use calorimetry to
calculate ΔH of diborane (B2H6). So we use Hess’s
Law and some reactions that we can determine
ΔH for.
• 2B (s) + 3H2 (g)  B2H6 (g)
• We then use the following data…
•
•
•
•
2B (s) + 3/2O2 (g)  B2O3 (s)
B2H6 (g) + 3O2 (g)  B2O3 (s) + 3H2O (g)
H2 (g) + ½ O2 (g)  H2O (l)
H2O (l)  H2O (g)
ΔH = -1273kJ
ΔH = -2035kJ
ΔH = -286kJ
ΔH = 44kJ
All you!
•
•
•
•
Given the following data…
2O3 (g)  3O2 (g)
O2 (g)  2O(g)
NO(g) + O3(g)  NO2(g) + O2 (g)
• Calculate H for this reaction…
• NO(g) + O(g)  NO2(g)
ΔH = -427kJ
ΔH = +495kJ
ΔH = -199kJ
Getting a Reaction Started:
Activation Energy
• CH4 + O2  CO2 + H2O + energy
• What happens when gas like methane is
pumped into a room with oxygen?
• Nothing.
• Just because 2 chemicals are in contact
with each other does not mean that a
reaction will occur even if it is exothermic.
• A spark or a flame is needed to start the
reaction and get the methane to burn in
oxygen.
Getting a Reaction Started:
Activation Energy
• The spark or flame supplies the energy needed
to jumpstart the reaction—called activation
energy.
Energy
Activation
Energy
Energy of
Reactants
-ΔH
Energy of
Products
Getting a Reaction Started:
Activation Energy
• The bigger the hill, the slower or less likely
the reaction will take place.
• The lower the hill, the faster the reaction
will take place.
• Some possible fuels have too high of Ea
and are not useful and some have to low
of a Ea and are dangerous.
Other Ways to get a Reaction to
Go!
• Grinding up the fuel (coal) which increases
the surface area will speed up the
reaction.
• Increasing the temperature of the fuel
mixture will increase the rate of the
reaction as well.
Changing Gears from Reactions
•We have been talking about the heat
gained or lost during a chemical reaction
and it has been a load of fun.
•Now we are going to look at how heat is
gained or lost when we look at the physical
changes of melting, boiling and
temperature change.
Today…
•If you missed yesterday copy this website.
•The answers are due on Monday.
• http://www.mrfischer.com/wpcontent/uploads/23-thermwebquestques.pdf
• By Monday BONUS points on Quest possible.
• Bring empty and clean 2L bottles get 1% added to
quest grade (Max 5%)
• Bring 1L bottle of vegetable oil (5%)
Heat to Change Temperature and
to Change Phase
• If ice turns into water, what is needed?
• If water turns into vapor, what is needed?
• If the temperature of water increases, what is
needed?
• HEAT!!!!
mass
q = mCpΔT
Change in
temperature
ΔT = Tf - Ti
heat
Specific heat
Amount of heat needed to increase the temp of 1g of a substance by 1ºC
Heat to Change Temperature and
to Change Phase
• Specific heat (Cp) is different for every
substance and it is different for each phase of a
given substance.
• Cp ice = 2.02 J/gºC
• Cp water = 4.2 J/gºC
• Cp vapor = 2.06 J/gºC
• Ex—How much heat is needed to raise the
temperature of 150g of water from 2.0ºC to
93ºC?
Heat to Change Temperature and
to Change Phase
• If ice is melted, heat is needed, but we
don’t look at the temperature.
• Energy added is used to stretch bonds not
make the particles move faster (T).
• Types of bonds…
• Intra-molecular—atoms are held together
inside a molecule.
• Inter-molecular—molecules are held
together in a substance.
Heat to Change Temperature and
to Change Phase
• The equation we need to determine the
heat necessary to melt a given amount of
solid is…
mass
q = mΔHfus
heat
Heat of Fusion
Amount of heat needed to melt 1g of a solid
Heat to Change Temperature and
to Change Phase
• Heat of fusion (ΔHfus) is different for
every substance.
• ΔHfus ice = 330 J/g
• Ex—How much heat is needed to melt
150g of ice?
Heat to Change Temperature and
to Change Phase
• If water is boiled, heat is needed, but we
don’t look at the temperature.
• Energy added is used to break bonds not
make the particles move faster (T).
Heat to Change Temperature and
to Change Phase
• The equation we need to determine the
heat necessary to boil a given amount of
liquid is…
mass
q = mΔHvap
heat
Heat of Vaporization
Amount of heat needed to boil 1g of a liquid
Heat to Change Temperature and
to Change Phase
• Heat of vaporization (ΔHvap) is different
for every substance.
• ΔHvap water = 2260 J/g
• Ex—How much heat is needed to boil 150g
of water?
Heat to Change Temperature and
to Change Phase
• Putting it all together…
Add heat & boil…
q = mΔHvap
G
Add heat and T
inc…q = mCpΔT
100ºC
T (ºC)
Add heat & melt…
q = mΔHfus
L
Add heat and T
inc…q = mCpΔT
0ºC
S
Add heat and T
inc…q = mCpΔT
Heat (q in Joules)
Ask this question: is the
substance changing
temperature or
changing phase?
1.
•
2.
•
3.
•
4.
•
5.
•
Try em!
If it is changing
temperature, which eq’n
works? If it is changing
phase, which eq’n
works?
How much heat is absorbed by a 6.00g piece of -13.0ºC ice cube
when it is heated to 0.0ºC?
160J
How much energy does it take to melt the 6.00g ice cube if it is
at its melting point?
1980J
How much energy is absorbed by 6.00g of liquid water at 0.0ºC
to bring it to water’s boiling point?
2500J
How much energy does it take to turn 6.00g of liquid water at
100.0ºC to steam?
13600J
How much energy is needed to take 6.00g of steam at 100.0ºC to
steam at 120ºC?
250J
OK...try this
• How much heat is needed to turn ice at -11ºC
into water at 55ºC?
Heat to Change Temperature and
to Change Phase
• If a piece of hot metal is dropped in a
beaker of cool water, what happens to
the temperature of the metal? The
water?
• So, if the water absorbs 100kJ of energy
the metal loses…
• 100kJ of energy.
• The metal’s temperature drops.
Heat to Change Temperature and
to Change Phase
• So, the heat lost by an object is gained by
another object.
• Heat lost = -q
• Heat gained = +q
• So, for the hot metal/cool water example, the
heat gained by the water (+qwater) equals the
heat lost by the metal (qm).
• +qwater = -qm
• qwater + qm = 0
Heat to Change Temperature and
to Change Phase
• If a piece of ice melts, where does the heat
come from?
• Something outside of the ice cube.
• If we place and ice cube in a glass of Kool-Aid
what supplies the heat to melt the ice?
• Mostly the Kool-Aid.
• So, if the ice absorbs 100kJ of energy the KoolAid loses…
• 100kJ of energy.
• The Kool-Aid’s temperature drops.
Heat to Change Temperature and
to Change Phase
• What if we have a 55.0g of a piece of
metal, say iron, at 99.8ºC and we place it
in a 225g of water at 21.0ºC.What is the
specific heat of the metal if the final
temperature of the water and Fe is 23ºC?
Heat to Change Temperature and
to Change Phase
•
•
•
•
•
•
•
Heat lost by iron is –qFe
Heat gained by water is +qH2O
-qFe = +qH2O
qFe + qH2O = 0
What happens to the iron as heat is lost?
Temperature drops.
What equation do we use for temperature
change?
• q = mCpΔT
Heat to Change Temperature and
to Change Phase
• What happens to the water as heat is
gained?
• Temperature rises.
• What equation do we use for temperature
change?
• q = mCpΔT
• So we can rewrite the previous eq’n as…
• (mCp ΔT)Fe + (mCp ΔT)H2O = 0
Heat to Change Temperature and
to Change Phase
• (mCpΔT)Fe + (mCp ΔT)H2O = 0
• (55.0g)(X)(–76.8ºC) + (225g)(4.2J/gºC)(2.0ºC)
=0
•
•
•
•
-4224g ºC X + 1890J = 0
-4224g ºC X = -1890J
X = -1890J / -4224g ºC
0.448 J/gºC
Heat to Change Temperature and
to Change Phase
• Another example…
• What is the minimum amount of ice at
0ºC that must be added to the contents
of a 340. mL glass of Kool-Aid to cool it
from 20.5ºC to 0.0ºC. Assume Cp of KoolAid is the same as liquid water and that
no heat is gained or lost to the
surroundings.
Heat to Change Temperature and
to Change Phase
• qice + qKoolAid = 0
• What happens to the ice when heat is
added to it?
• What happens to the Kool-Aid as heat is
lost?
• The q’s then are…
• (mΔHfus)ice + (mCp Δ T)KA = 0
• (m)(330J/g)+(340g)(4.2J/gºC)(-20.5ºC)=0
• m = 88.7g ice needed
Old Fuel
• Coal, oil and natural gas possess many of
the properties needed in a fuel.
• So, most of the energy we use comes
from these sources.
• These fossil fuels can be thought of as
sunshine in the solid, liquid and gas state.
• Sunlight was captured millions of years
ago in green plants that over the years has
decomposed and highly compressed into
the fossil fuels we use today.
Old Fuel
• 2800kJ + CO2 + H2O  C6H12O6 + O2
• Plants require about 2800kJ of energy
from the sun for each mole of glucose they
produce.
• On the other hand we use the 2800kJ of
energy per mole of glucose we eat.
• This energy is converted into the energy
that our muscles and nerves use
throughout the day.
Coal
• When the Industrial Revolution began,
wood was the major source of fuel in
England.
• Over a short time all the forests were cut
down and wood was scarce…so coal took
over.
• Burning 1g of coal produces 30kJ of heat
while burning 1g of wood produces only
10-14kJ of heat.
• Coal was definitely the choice.
Coal
• Coal has a chemical formula of
C135H96O9NS.
• In addition samples of coal also contain
small amounts of Si, Na, Ca, Al, Ni, Cu,
Zn, As, Pb and Hg.
• The more impurities the lower the grade
and the lower the amount of heat released
during the burning of coal.
Try This One
• Assuming the composition of coal can be
approximated by the previous given
chemical formula, calculate the mass of
carbon (in tons) contained in 1.5 million
tons of coal, which is the amount of coal
that a typical power plant would burn.
(Hint: Mass %)
Petroleum
• Around 1950, petroleum surpassed coal
as the major energy source in the US.
• It is liquid so it is easier to pump from the
ground reserves, transported via pipelines
and fed automatically to its point of use.
• Also petroleum yields about 48kJ per gram
burned—much more than coal.
Petroleum
• However, crude oil must be processed
before it can be used.
• The crude oil is refined by a process called
distillation into many different usable forms
of fuels.
• It can be separated into gasoline,
kerosene, gas oil, lubricating oil and
petroleum gas.
Manipulating Molecules
• Research has found that not all compounds
distilled from crude oil are useful for desired
applications.
• Chemists have devised ways to take these high
molecular weight compounds and create smaller
more usable compounds through a process
called cracking.
• C16H34 is a byproduct of distillation but is not
very useful.
• C16H34  C8H18 + C8H16 or
• C16H34  C5H12 + C11H22
Seeking Substitutes
• Because the world’s coal supply is much
greater than our available oil reserves,
there is interest in converting coal into
gaseous and liquid fuels that are identical
with or similar to petroleum products.
• An old technology that does this is blowing
steam over hot carbon called coke.
• Coke is the impure carbon that remains
after volatile components have been
distilled from coal.
• C(s) + H2O(g)  CO(g) + H2(g)
Seeking Substitutes
• The CO and H2 are called water gas and
were used as energy to light cities.
• Fischer-Tropsch process for producing
synthetic gasoline uses this reaction.
• The CO and H2 are passed over an iron or
cobalt catalyst which promotes the
formation of hydrocarbons.
• The hydrocarbons range in size from
methane to 5-8 carbon atoms (that are
typically used in gasoline).
Seeking Substitutes
• This process is economically feasible in
locations where coal is cheap and plentiful
and oil is scarce and expensive.
• This is the case in South Africa, where
40% of the gasoline is obtained from coal.
• In the future, such technology might
become competitive in other parts of the
world.
Seeking Substitutes
• The concerns about dwindling supplies of
petroleum have also led to the use of
renewable energy sources.
• This generally refers to biomass which are
materials produced by biological
processes.
• Wood is one such source, but there is far
too little wood to meet our energy
demands.
• Plus we would be destroying good CO2
absorbers.
Seeking Substitutes
• Our favorite, ethanol (C2H5OH) is another
alternative biomass fuel getting a lot of press of
late.
• Ethanol is formed by the fermentation of
carbohydrates such as starches and sugars.
• Enzymes released by yeast cells catalyze the
reaction that is typified by…
• C6H12O6  2 C2H5OH + 2 CO2
• The burning of ethanol releases 1367kJ per mole
burned. (~30kJ/g—lower than 48kJ/g produced by
gasoline)
Seeking Substitutes
• The burning of ethanol releases 1367kJ per
mole burned.
• Corn is being used to create ethanol and
added to unleaded gas at 85:15 to create
E85 gas.
• In general, E85 gas is cheaper than
unleaded gas, but you can only use E85 gas
in certain vehicles.
• Should Oil Companies be banned from
Owning Ethanol Plants ?
Seeking Substitutes
• Ethanol or flex-fuel cars are common in
countries such as Brazil.
• They farm sugar cane and convert it to
ethanol and run any mixture of ethanol-gas
they choose.
• But by using computer sensors that adjust to
whatever mix is in the tank, flex car engines
run on either ethanol, gasoline, or any
combination of the two.
• Gas-electric hybrids are another option.
Seeking Substitutes
• Unlike hybrids sold in the US, for example,
flex cars sold in Brazil don't cost any more
than traditional models.
• In fact, some models are only available with
flex engines now.
• Ethanol engines use 25 percent more
ethanol per mile than gasoline. But ethanol
usually sells at somewhere between a third
to half of the price of gas.
Seeking Substitutes
• Another potential energy source is a
commodity that is cheap, always present in
abundant supply and is always being
renewed.
• It is garbage.
Seeking Substitutes
• Elk River Resource Recovery Facility (ERRRF) in
Hennepin, MN processes garbage into refuse
derived fuel (RDF).
• ERRRF serves five area counties. Hennepin
County contracts to deliver up to 235,000 tons of
garbage to ERRRF each year.
• The RDF is transported to a nearby power plant,
where it is combusted to generate electricity.
• The RDF from Hennepin County garbage produces
enough electricity to provide power to the
equivalent of 12,700 homes each year.
Seeking Substitutes
• This resource recovery approach
simultaneously addresses two major
problems…
• The growing need for energy
• The growing mountain of waste
Write
• The Elk River Resource Recovery Facility has been
the subject of a great deal of controversy for the
county residents. The idea of generating usable
energy from trash sounds great, until the facility is built
in your neighborhood. This is a problem faced by the
homeowners and residents in the area surrounding
the plant. To address residents’ concerns, an open
meeting between the residents and representatives of
the plant is scheduled. Managers from the plant,
engineers, and representatives of the state pollution
control agency will be present. Prepare a list of
questions that you, as a resident in this area, would
like to see addressed at this meeting.
The Case for Conservation
• The fundamental feature of the universe is that
energy and matter are conserved.
• However the process of combustion degrades
both energy and matter, converting them to less
useful forms.
• As residents of the universe, we have no choice
but to obey its unavoidable laws.
• The planet’s fossil fuel stores are limited and
although we could go many years without
running out, there will come an end.
The Case for Conservation
• The demands of the power plants in the world
for coal, oil and gas are huge.
• Fibers, plastics, rubber, dyes, medicines, and
pharmaceuticals are currently produced from
petroleum.
• Once the petroleum is gone, we will need to
find a different way to make these as well.
• On a positive note, the world is aware of this
situation and many have been working to find
better alternatives all the time.
The Case for Conservation
• To a considerable extent, taste ultimately
influences what technology can do to conserve
energy.
• As individuals and as a society, we must decide
what sacrifices we are willing to make in speed,
comfort and convenience for the sake of our
dwindling fuel supplies and the good of the
planet.
The Case for Conservation
• The costs might include higher taxes, more
expensive gasoline, and electricity, fewer and
slower cars, warmer buildings in the summer
and cooler ones in the winter.
• One thing seems clear: the best time to
examine our options, our priorities, and our will
is before we face another full blown energy
crisis.
Review
• What does the 1st Law of Thermodynamics
state? (a.k.a. Law of Conservation of
Energy)
• Define energy.
• Define work.
• Define heat.
• What is the unit for energy?
• What is the difference between and exo
and endothermic reaction?
Review
• Define activation energy and draw an
energy graph showing an exothermic
reaction.
• What is combustion?
• Draw these molecules…O2, CO2, H2O,
CH4, C3H8)
• What is bond energy?
• Is bond breaking an endo or exothermic
process?
Review
• Is bond forming an endo or exothermic
process?
• What is the energy given off or absorbed
for the reaction of octane (C8H18) with O2
to form CO2 and H2O?
• What are three main fossil fuels used
today?
• How are fossil fuels like sunshine in the
solid, liquid or gas form.
Review
• How does the 1st Law of Thermodynamics
illustrated through fossil fuels?
• How does the 1st Law of Thermodynamics
illustrated through photosynthesis?
• What is “cracking” and when is it used
during fossil fuel refinement?
• Rank the following in order from lowest to
highest energy output per gram used:
petroleum, coal, ethanol, wood.
Review
• Give a reason why it is good to use wood
as fuel and one that is not good.
• Give a reason why it is good to use coal
as fuel and one that is not good.
• Give a reason why it is good to use
petroleum as fuel and one that is not good.
• Give a reason why it is good to use
ethanol as fuel and one that is not good.
Review
• How is coal converted to synthetic
gasoline?
• What is E85?
• How is ethanol made?
• What are flex-fuel cars?
• Who is ahead of the US in the usage of
ethanol fueled cars?
• What is being done in Hennepin MN?
The Other Side of the
Inconvenient Truth
• Get ready to take Notes on some videos.
Message to Seniors…
• "Senior skip day may result in the loss of special
privileges planned for your class, including your
senior day breakfast, the senior cookout on your
last day, and of course Baccalaureate and
Graduation. This class at our school gets out
waaaaay earlier than most schools with the Senior
Seminar, so there should be no need for a skip day.
Please know that the administration will find out
and will follow up with the appropriate
consequences."
• So sayeth el Bridges