chapter 3.b. petroleum: an energy source
DESCRIPTION
Chapter 3.B. Petroleum: An Energy Source. Do Now. Read Chem Quandary #1 on page 237 Answer 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. - PowerPoint PPT PresentationTRANSCRIPT
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