Chapter 3.B. Petroleum: An Energy Source

Chapter 3.B. Petroleum: An Energy Source

Do Now

Read Chem Quandary #1 on page 237Answer questions: a, b, and c

Objectives

1. SWBAT define kinetic, potential, chemical, thermal, endothermic, exothermic and energy conversions.

2. SWBAT state the law of conservation of energy.

B.1. Energy and Fossil Fuels

Petroleum: remains of prehistoric plants and animals

Fossil Fuels: petroleum, natural gas, and coal (buried sunshine)

500 million years ago – living matter died and became covered by sediments

Through pressure, heat, and microbes – became petroleum

NON RENEWABLE RESOURCE

Energy

Energy: Ability to do workA. Potential Energy- stored energy (energy

of position)B. Kinetic Energy – motionC. Chemical Energy- stored in chemical

bondsD. Thermal Energy- heat

Think-Pair-Share

What type of energy?1. Petroleum 2. Boiling Water3. Running4. Compressed Spring5. Natural Gas6. Rock Rolling Down a Hill

Combustion

Burning of methaneIn order for a chemical reaction to happen

we must break bonds and build different bonds.

CH4 + 2O2 CO2 + 2H2O + energy

Types of Reactions

Endothermic; requires a net input of energy (reactants)

Exothermic: requires a net output of energy (products)

If a reaction is exothermic, then the reverse is endothermic

EX.2H2 + O2 2H2O + O2 + Energy

VS.

Energy + O2 + 2H2O 2H2 + O2

B.2 Energy Conversions

Fig. A

Fig. B

Fig. EFig. D

Fig. C

Law of Conservation of Energy

Energy is not used up or lost – just changes form

EX. Potential to Kinetic

Think-Pair-Share

Turn to pg. 243 and do #1-2

Homework

Pg. 258# 1-3, 5, 7-12

Do Now

Write down the types of energy involved in each conversionA. Pencil falling off a deskB. Hair DryerC. Eating a SandwichD. Car Driving

Objectives

1. SWBAT explain why energy conversions are never 100% efficient and calculate the cost associated with various energy conversions.

2. SWBAT define heat of combustion and use it in various calculations, and explain why thermal energy produced per gram is a primary factor in choosing types of hydrocarbons for burning

B.4. Energy Efficiency

Need to increase efficiency of energy transfers. (energy “lost” as heat)Solar Cells: Solar energy to electrical energyFuel Cells: chemical energy to electrical energy

B.5. Energy Conversion Efficiency

Problem: Assume that your family drives 225 mile each week and that car can travel 23.0 miles on one gallon of gasoline. How much gasoline does that car use in one year?

225 mi 23.0 mi 1 wk 1 gal

Think-Pair-Share

Turn to pg. 245 and answer questions #1-4 with a partner.

B.6 Combustion

Lab pg. 248

Alkane + _O2 _CO2 + _H2O + thermal energy

B.7. Using Heats of Combustions

2C2H6 + 7O2 4CO2 + 6H2O + ? thermal energy

2C2H6 + 7O2 4CO2 + 6H2O + 3120 kJ

Table 3.6

pg. 250

Do Now

Assume the molar heat of combustion of carbon contained in coal is 394 kJ/mol C.

1. Write a chemical equation for the combustion of coal (include thermal energy).

Objectives

1. SWBAT describe and explain why and give examples of 4 ways that chemists alter fuels: cracking, octane rating, oxygenated fuels, and lead based additives

2. SWBAT to answer sample conversion problems.

Sample Problem

How much energy (in kilojoules) is released by burning of 25 mol hexane?

Think-Pair-Share

Turn to pg. 253 and do #1, 2a, 3a

Worksheet

Do Now

How much thermal energy is released from a reaction that has 15 mol of pentane?

2. How much thermal energy is released from a reaction of 20 grams of butane?

B.9 Altering Fuels

Chemists have been altering fuels to increase needs of consumers.

1. Cracking:Takes large hydrocarbons and breaks them

down into smaller, more useable onesUse of a catalystEx. kerosene to gasoline

C16H34 C8H18 C8H18

2. Octane Rating

Gasoline can burn prematurely in the cylinders of the engine (knocking or pinging)

Isooctane has excellent combustion properties

2. Octane Rating

Octane Rating: fuels burning efficiencyHigher the octane rating the better the

less knockingUsually an average between running

engine and one with a load (passengers)Isooctane has octane rating of 100 and straight chain heptane has zero.

2. Octane Rating

Back in the 1920s-1970s, (C2H4) 4Pb was added to straight chain gasoline to increase efficiency (leaded fuel)

MTBE: (methyl tetriary-butyl ether) contaimnation of water supply

3. Oxygenated Fuels

Blended gasoline to increase octane rating (additives that contain oxygen)

Less energy per gallon but have more efficient burning with less pollutants.

Ex. Methanol can be added.

3. Oxygenated Fuels

Isomerization: converting straight chains to branched

Think-Pair-Share

To start to think about your end of unit project complete the following:

Pg. 257 #1-6