1. Chapter 4: Energy, Chemistry, and Society

2. ENERGY? What do you think of when you hear the word
Like the energy of a crowd,
You can’t see it,
Can’t measure it,
But you know it is there.

3. Terms that need to be defined:
Energy is the capacity to do work.
Work is movement against a force (w = f x d).
Heat is energy that flows from a hotter to a colder object.
Temperature determines the direction of heat flow.
Heat is a consequence of motion at the molecular level; temperature is a measure of the average speed of that motion.
4.1

4. 1 kcal = 1000 cal = 1 Cal (1 dietary cal)
What are units of heat?
The joule (J): 1 J is the amount of energy required to raise a 1-kg object 10 cm against the force of gravity.
The calorie (cal): 1 cal is the amount of heat required to raise the temperature of 1 g of water by 1 oC.
1 calorie = J
1 kcal = 1000 cal = 1 Cal (1 dietary cal)
So that 450 Cal doughnut is really 450,000 calories!
4.1

5. First law of thermodynamics potential/kinetic energy
First Law: The energy of the universe is constant,
or, energy can neither be created nor destroyed; but it can be converted from one form to another.
Potential energy is energy due to position or composition.
Kinetic energy is energy due to movement.
4.2

6. Diagram of a Power Plant
electricity
work
heat
4.2

7. Power plants are inevitably inefficient
Potential energy
(chemical bonds)
The First Law of Thermodynamics
Energy is neither created nor destroyed, but may be transformed from one form to another.
burner
Heat energy
Taking random, thermal energy and transforming it into ordered work goes against the
Second Law of Thermodynamics.
gas turbine
Mechanical energy
Second Law of Thermodynamics
The entropy of the universe is increasing.
generator
Electrical energy
There is no free lunch!
4.2

8. Bomb calorimeters can be used to determine the heat of combustion.
If you test a reaction that releases heat, the temperature of the water will increase.
4.3

9. Energy is released in this process called combustion.
Hydrocarbon fuels like methane (CH4) burn in the presence of oxygen to produce carbon dioxide and water.
Energy is released in this process called combustion.
CH4(g) O2(g) CO2(g) H2O(l) + ENERGY
When energy is released during the course of a chemical reaction, it is said to be an EXOTHERMIC reaction.
The combustion of methane gas releases 50.1 kJ/g of CH4
This is the equivalent of kJ/mol CH4
4.3

10. CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)
Net energy
change is
kJ/mol CH4
Exothermic reaction
The products are lower in energy than the reactants.
Exothermic reaction: DE is a negative value
4.3

11. Activation energy is the energy required to initiate the reaction.
Molecules must possess enough energy so that their collisions will be productive- leading to products.
Exothermic reaction
ENDOTHERMIC reactions will have products higher in energy
(DE will be positive) than the reactants;
there will still be a required activation energy.
4.3

12. Energy Changes at the Molecular Level
The energy changes are due to the rearrangement of the atoms of the reactants and products;
it is the breaking and forming of bonds that dictates if a reaction will be endothermic or exothermic.
Bond energy is the amount of energy that must be absorbed to break a chemical bond.
energy
Breaking bonds ALWAYS requires energy!
4.4

13. 4.4

14. Consider: 2 H O H2O
Bonds breaking
2 H-H + O=O
Bonds forming
4 O-H
(2 H-O-H)
4.4

15. History of U.S. Energy Consumption by Source 1800-2000
1 EJ = 1018 J
4.5

16. 18.7% increase each year

17. OPEC Oil “Proven” Reserves!
Not proven
by anybody!
Oil and Gas Journal July 28, 2003, Rafael Sandrea, “OPECs next challenge, rethinking their quota system”. There was a discussion of a new quota system, and countries increased their reserves, presumably thinking that it would help them get higher quotas
Proved Reserves from the BP Statistical Review They start in 1980 EIA production data at
Kuwait leak January 2007 of 2001 documents
24 billion proved, 48 billion probable
Estimate of 2 billion barrels loss for Kuwait in the first Gulf War in the World Energy Council 2007 Survey of Energy Resources page 59
I include 2 billion barrels for oil burned in the first Gulf War, estimated in
Accurate reserve estimates for OPEC countries are closely guarded state secrets
Values for 1983 are probably accurate (for 1983)
430Gb rise in reserves, no adjustment for 193Gb produced since 1980
These questionable reserves are 45% of world oil reserves used by IPCC!
A recent leak of Kuwait Petroleum Company documents showed the actual reserves are only 48Gb (official reserves are 102Gb)
1980 Kuwait reserves adjusted for production since then are 55Gb
From BP Statistical Review
Gb = billions of barrels

18. World Oil Production Peaked in May 2005 non-OPEC Peaked in 2004
Saudi Arabia peaked in 2005,
Russia appears to have peaked
IEA still
predicts
an increase
(May 19, 2009)
MBD
Year

19. Existing Oil Fields are in Decline
Existing oil fields are declining at - 6.7% per year (IEA 2008)
For 2005 to 2030 the world needs 45 mbd of new production –
just to maintain flat production
The projected growth requires
discovery of = 57 mbd of new oil!
57 ÷ 9 = ~6+ We need 6 new Saudi Arabias!

20. How Do Different Fuels Stack Up?
High E content and the only product of its combustion is water!
4.6

21. Coal
Coal is a complex mixture of substances. Although not a single compound, coal can
be approximated by the chemical formula
C135H96O9NS.
U.S. reserve estimates range from 150 to 250 years.
4.6

22. Petroleum – from where does the U.S. import it?
2005: U.S. consumption was almost 22 billion barrels A DAY.
Over 60% of it was imported.
The U.S. has 5% of the world’s population, yet consumes 25% of the oil produced worldwide.
4.7

23. One of the drawbacks to petroleum is that it must be refined before use.
4.7

24. A Port Arthur, Texas Oil Refinery
A Port Arthur, TX Oil Refinery
4.7

25. How do we use each barrel (just under 45 gal) of petroleum?
This 1.25 gal includes nonrenewable feedstocks for all plastics, pharmaceuticals, fabrics and other carbon-based products.
Over 87% of each barrel is used for transportation and heating.
4.7

26. Gasoline Additives
Elimination of octane enhancing tetraethyl lead (TEL) created a need to find substitutes.
MTBE –methyl tertiary-butyl ether
Ethanol (ethyl alcohol)
Human health effects of exposure to MTBE are not known.
4.9

27. Fuel Alternatives
Biodiesel fuel use is on the rise. Made from natural, renewable sources (veg oils, animal fats), it
can be used as pure fuel or blended with petroleum.
Ethanol is renewable, but more expensive than gasoline.
It takes more energy to produce a gallon of ethanol than you will obtain from burning it.
Controversy: National Corn Growers vs. American Petroleum Institute.
4.10