FRONT CLASSROOM

A FC

D

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B IG

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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