FRONT CLASSROOM
A FC
D
E
B IG
H
Please, join your groups and identify ONE important idea you learned last class.
NATS 101NATS 101 : “The World We Create”: “The World We Create”
01/21
UNIT 1: Energy Sources,
Conventional or Alternative?
Energy Sources
• Renewable sources - 6%• Non-renewable sources - 94%
– Of which 85.3% comes from Fossil Fuels (Hydrocarbons) Combustion
Close to 40% comes from Petroleum
Limited Supply but High Demand!
WHO HAS THE OIL AND WHO USES IT?
What possible consequences:Economic Social Political
concerning petroleum use are suggested by these comparisons? (at least one of each)
Think of current and future issues associated with the distribution of oil and its use.
Think, for example: What may happen as China develops? What could happen if the US loses access
to Middle East reserves? ETC
Who has it? Who Wants it?
Then, let’s see what the data implies:
You have 10 minutesSelect a note taker and a
spokesperson
By the end of the class, you should be able to:
Explain why petroleum is a valuable fossil fuel;
Given a set of chemical compounds, predict which of them will produce more energy during combustion based on their chemical composition;
Today: Why Petroleum?
C4H10 C2H6O C2H6 C2H4O2
Why Petroleum?
• In your groups discuss:– Why don’t we all drive electric vehicles if
there are so many issues associated with using petroleum as a source of energy?.
You Have 2 Minutes
The Reasons• Poor performance (Heavy, needs to be recharged).
Compare
Electrical batteries supply energy at a rate of
6500 joules (J) per second (6500 Watts = 6.5 kW)
1 Liter (1 L) of gasoline transfers 34,000,000 J per second when you burn it
34 Megajoules/s= 34 MW
1 Liter/s
~ 5,200 times fasterPower
Energy
The Reasons
A large 2000 MW power station
= 59pumps
Petroleum is a highly concentrated energy source!
Why?Where is the energy coming from?
Hydrocarbons are combustible. They react with oxygen in a
Combustion Reaction.
The Chemistry of Petroleum
Products
Carbon Dioxide Water
ENERGY
Hydrocarbon Oxygen
Reactants
Heat of ReactionEp
CH4 + 2 O2 CO2 + 2 H2O
CH4 + 2 O2
Net Energy Released = -804 kJ = qrxn
4 x 414 + 4 x 249
C + H + H + H + H + O + O + O + O
+ 2652Dissociati
on
Energy needed to break bonds.
CO2 + 2 H2O
- 3456
-4x400 – 4x464
Formation
Energy released when forming bonds.
Energy Graphs
Products
ENERGYRELEASED
EXOTHERMIC
Reactants
Reactants
ProductsENERGY
ABSORBED
ENDOTHERMIC
Heat of ReactionDifferent substances produce different amounts of
energy during Combustion Reactions.
-5470
-890 -726
-6000
-5000
-4000
-3000
-2000
-1000
0Octane Methane Methanol
Energy released in kJ/mol (when 6.02 x 1023 molecules are burned)
MethaneCH4
MethanolCH4O
OctaneC8H18
Explain the Difference• Give a possible explanation to the difference in
the energy released when octane, methane, and methanol are burned.
You have 5 minutes
MethaneCH4
MethanolCH4O
OctaneC8H18
E
CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)
CH4O(g) + 3/2 O2(g) CO2(g) + 2 H2O(l)
C8H18(g) + 25/2 O2(g) 8 CO2(g) + 9 H2O(l)
The ReasonDuring a chemical reaction some bonds are broken
and some new bonds are formed.
Breaking bonds requires energyForming bonds releases energy
NET RESULT?
The more oxygen can combine with other atoms to form new bonds, the more energy will be released.
The ReasonDuring a chemical reaction some bonds are broken
and some new bonds are formed.
Breaking bonds requires energyForming bonds releases energy
We are making fewer bonds with oxygen because one is already made.
NET RESULT?
You DecideConsider the following two chemical compounds:
Glucose C6H12O6
Oleic Acid C18H34O2
(main constituent of plant oils)
Which of these two compounds will generate more energy when burned? Why?
What are the implications for your body?
Oleic acid is not only a larger molecule but is less oxygenated than glucose. Thus, it generates more
energy when burned.
1 g the carbohydrate 17 kJ = 4.1 Cal1 g of the fat 39 kJ = 9.3 Cal
Application • In your groups, explore what happens when you
combine each of the following substances with water:
A) Ammonium Nitrate (NH4NO3) B) Lithium Chloride (LiCl)
– Add one cap of water at a time!!– Make sure to record observations!
You Have 10 Minutes
• Generate an hypothesis in terms of bonds breaking and forming to explain any differences you observe.
• Compare in an energy graph the energy of reactants and products.
Exothermic LiCl(s) + H2O(l) Li+(aq) + Cl-(aq) Lithium Chloride Water Lithium ion Chloride ion
LiCl + H2O
PE
Li+ (aq) + Cl-(aq)
Reactants
Products
ENERGYRELEASED
Total energy is
CONSERVED
Strong Interaction with H2O
Endothermic NH4NO3(s) + H2O(l) NH4
+(aq) + NO3-(aq)
Ammonium Nitrate Water Ammonium ion Nitrate ion
NH4NO3 + H2O
PENH4
+ + NO3-
Reactants
Products
ENERGYABSORBED
Total energy is
CONSERVED
Homework (Due 01/26/10)
IMPORTANT
CHECK D2L FOR THE ASSIGNMENT AND
DETAILED INSTRUCTIONS
(CONTENT SECTION)
Also Check the Support Reading