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Unit 3B&C Study Guide
Petroleum: An Energy and Building-Material Source
Why are hydrocarbons commonly used as fuels?
Why are carbon-based molecules versatile as chemical building blocks?
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Date: ___________Right Now
Quick Notes: Energy vs TemperatureEnergy Temperature
Definition
Units
Examples
What happens when you have a lot of:
How you measure:
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Energy Conversions in a Car Date: ______________
In one sense, an automobile – whether powered by electricity, gasoline, or solar energy can be considered a collection of energy-converting devices. The principle behind a car’s engine is an internal combustion engine—a tiny amount of fuel is put in a small, enclosed space and ignited. This releases energy which allows a piston to move. Currently, gasoline is the preferred fuel for the average car. However, gasoline-powered cars are very inefficient. Only about 18% of crude oil becomes gasoline. The combustion of gasoline produces carbon dioxide and water along with pollutants such as carbon monoxide, nitrogen oxides, and unburned hydrocarbons.
1. How does car movement obey the Law of Conservation of Energy?
2. Name the type of energy (kinetic energy, potential energy, or heat) involved in each step required to move a car.
3. According to the diagram to the right how much energy is “lost”?
4. Energy is always conserved. How is it possible that energy is “lost”?
5. What really happens to the “lost” energy from gasoline?
6. People have tried to increase the efficiency of the internal combustion energy, but they are never able to obtain 100 % efficiency. Hypothesize why it is impossible to obtain technology that achieves full efficiency.
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Energy Vocab Date: ______________Skim through sections 3B&C to find the major vocabulary words. For each word, write the definition. Then use the book to come up with an example or a statement that correctly identifies the word: context from the text that will help you remember what the word means. The memory hook can be a picture, an example, or a page number.
Word Definition in your own words Memory Hook
Potential energy
Kinetic energy
Endothermic
Exothermic
Law of Conservation Energy
Specific Heat Capacity
Heat of Combustion
Functional Group
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Heat Transfer Date:________________Not all materials respond the same when they absorb heat energy. Some materials need a lot of energy to make the temperature rise, while others don’t need as much. You will practice heat calculations to determine the relationships that exist with heat.
Background Information:1. What is heat?
2. What is the equation that calculates the amount of heat?
3. In what direction is heat always transferred?
4. What does a negative heat mean? When will this happen?
5. What does a positive heat mean? When will this happen?
Example: Calculating Heat transfer for Ice in Water6. What are the variables that you need to calculate the heat transferred?
a. The specific heat of water in joules?
b. What is the mass of the water used (Hint: the density of water is 1 g/mL)?
c. How much did the temperature of the water change?
7. Calculate the heat transferred (in Joules) for water. Show your work.
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Relationship between Heat and Specific Heat 1. Run ScienceLab/ChemSimulation/Heat_Metal_Ice.html 2. Follow the procedure below for Silver, Gold, Copper, and Iron
a. Click on a metalb. Change the starting temperature of the metal to 220 ˚C.c. Click on start.d. Record the variables needed to calculate the amount of heat transferred.e. Calculate the heat transferred – show your work!f. Click Reset
Silver Gold Copper Iron
Specific Heat of the Metal (J/g ˚C)
Specific Heat of Water (J/g ˚C)
Mass of Water Used (g)
Change of Temperature of the water (˚C)
Heat is transferred from:
Heat is transferred to:
Calculate the Heat Transferred for the water (J)
Heat Transferred for the solid?
3. What is the relationship between the specific heat of the metal and the amount of heat transferred?(Direct or Indirect?!?!)
4. Water has a very large specific heat. Is it easy to hard to change the temperature of a body of water?
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Identifying Metal from Specific Heat Date: _________________SHOW YOUR WORK FOR ALL CALCULATIONS!
1. What was the final temperature of the metal?a. Trial 1 b. Trial 2
2. What was the ΔT for the metal?a. Trial 1 b. Trial 2
3. What was the ΔT for the water?a. Trial 1 b. Trial 2
4. Calculate the heat change for the water. (Specific heat capacity (C) for water is 4.184 J/goC.)a. Trial 1 b. Trial 2
5. Calculate the heat change for the metal. (Remember heat can never be created or destroyed)a. Trial 1 b. Trial 2
6. Calculate the specific heat of the metal.a. Trial 1 b. Trial 2
7. Use the data table to identify the metal used in the experiment.
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Describing Energy Notes Date: __________________
Energy is the ability to cause change. In chemistry we deal with two main forms of energy: Kinetic Energy (the energy of movement) and Potential Energy (the stored energy). Thermal Energy is the combination of kinetic and potential energy. We can describe energy by two terms: Exothermic and Endothermic. These terms are opposites of each other.
Exothermic Endothermic
What do the prefixes mean?
What happens to energy of the reaction?
What happens to energy of the surroundings?
What happens to temperature of the
surrounding?
Compare the potential energy of the reactants and
the products.
What does the energy graph look like?
What is the general chemical equation?
Classify the following events as exothermic (exo) or endothermic (endo).
1. Releases heat: __________
2. Absorbs heat: __________
3. Heat is found with the reactants: __________
4. Heat is found with the products: __________
5. Bouncing a ball: __________
6. Making ice cubes: __________
7. Cooking an egg: __________
8. Burning a match: __________
9. Formation of clouds: __________
10. Evaporating water: __________
11. Photosynthesis: __________
12. Cellular Respiration: __________
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Date: ___________Right Now
Quick Notes:
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3B7 Supplement: Using Heats of Combustion Date: ______________With enough oxygen gas present in a reaction, complete combustion occurs. Complete combustion can be described by the chemical equation: hydrocarbon and oxygen gas react forming carbon dioxide, water, and heat. Because combustion is a highly exothermic reaction, heat—thermal energy—is written as a product. A reaction is complete when the correct quantity of heat—thermal energy—is included. The total thermal energy is the quantity of hydrocarbon burned multiplied by the heat of combustion. Heats of combustion can either be given in terms of KJ/mole or KJ/g. In a balanced reaction you know the number of moles, therefore you need to use KJ/mole. When you know the mass burned you use KJ/g.
1. Coal is simply carbon. Carbon has a Heat of Combustion of 32.8 KJ/g and a Molar Heat of Combustion of 394 KJ/mol.a. Write a balanced chemical equation for the combustion of coal.
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b. How much energy is released in the complete combustion of carbon?
c. An average grill uses 720 g of carbon. For the complete combustion of a grill filled with carbon, how much energy is released?
2. Ethane is the second-largest component of natural gas. Ethane’s Heat of Combustion is 52.0 KJ/g and a Molar Heat of Combustion is 1560 KJ/mole.
a. Write a balanced chemical equation for the combustion of ethane.
b. How much energy is released in the complete combustion of ethane?
c. If you were to burn 5 grams of ethane, how much of energy is released?
3. The major component in gasoline is octane. Octane has a Heat of Combustion of 47.8 KJ/g and a Molar Heat of Combustion of 5,450 KJ/mole.
a. Write a balanced chemical equation for the combustion of gasoline. (Hint: the coefficient for octane is 2.)
b. How much energy is released in the complete combustion of octane?
c. A gallon of gasoline contains 2660 g of octane. For the complete combustion of 1 gallon of gasoline, how much energy is released?
4. Based on the heats of combustion for carbon, ethanol and octane that you used in this activity, what is the relationship between the number of carbon atoms and the Heat of Combustion? (Direct or Indirect?!?!)
5. Gram for gram, which is the better fuel – carbon or octane? Explain.
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Extra Credit: Calculating the amount of gasoline Date: __________________Complete the questions on a SEPARATE page and turn in no later than the day of the 3B/C test. Show ALL WORK for ANY credit. Each correct answer will give you 0.5 points EC.
Example: Let’s assume your family drives 200 miles each week and that the car can travel 25 miles on one gallon of gasoline. How much gasoline does the car use in one year? And how much does that cost?
Some conversions needed: 200 miles 25 miles 52 weeks 1 week 1 gallon 1 year
200 miles x 1 gallon x 52 weeks = 416 gallons in a year1 week 25 miles 1 year
And if gasoline costs $3 per gallon: 416 x $3 = $ 1,248
1. In one year in a car that averages 23.0 miles per gallon and travels 11,000 miles annually:a.How much fuel will be burned in a year?
b.How much does the yearly amount of fuel cost?
c. How many gallons of gasoline are wasted if cars only use 25% of energy released by burning gas?
d. How much money is lost due to inefficiency?
2. In one year in a hybrid-powered car that averages 50.0 miles per gallon and travels 11,000 miles annually:a.How much fuel will be burned in a year?
b.How much does the yearly amount of fuel cost?
c. How many gallons of gasoline are wasted if cars only use 25% of energy released by burning gas?
d. How much money is lost due to inefficiency?
3. Suppose a new car averages 70 miles per gallon and has an engine with 40% efficiency. How much fuel would be saved annually?
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3B9 Reading Guide: Altering Fuels Date: ________________As you read the section, complete the chart below by describing some ways that fuels are altered for gasoline engines. Use your own words.
Why must fuels be altered?
Process Description Examples
Cracking
Alteration of octane rating
Oxygenated fuels
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Date: ___________Right Now
Quick Notes:
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3C4-6 Reading Guide: Functional Groups Date: ________________
A functional group is a cluster of atoms that is found in various molecules. The group gives the molecule its characteristic properties. Several groups may occur in one molecule which would give the molecule a mixture of properties.
Note: R stands for the rest of the molecule, other than the functional group, and signifies a group of atoms including at least one carbon atom bonded to the functional group.
Name General Formula Suffix of Name Major Use Example
Alkene CxH2x -ene Manufacturing plastics Propene
Alkyne
Alcohol
Ester
Carboxylic Acid
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Date: ___________Right Now
Quick Notes:
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The Builder Molecules Date:___________1. What elements are present in an organic compound?
2. What happens between atoms in a covalent bond? Why do elements form covalent bonds?
3. How many covalent bonds do the following elements make?
a. Carbon: _______
b. Hydrogen: _______
c. Oxygen: _______
4. Compare the covalent bonds by filling out the table below
Type of bondNumber of
Electron Pairs Shared
How is it represented?
Relative length of bond
Relative amount of movement in
atoms
Relative Strength of
bond
Single covalent
Double Covalent
Triple Covalent
5. Use the models to find the unique features of functional groups.Type of
MoleculeExample 1 Name
& Structural FormulaExample 2 Name
& Structural FormulaWhat three things do the
examples have in common?
Alkene
Alkyne
Alcohol
Ester
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Carboxylic Acid
3C6 Supplement: Builder Molecules Date: ____________
Compounds are classified according to the functional group that is present in their molecular structure. Find and circle the functional group in each molecule, and identify it as a carboxylic acid, alcohol, ester, alkane, or none of the above.
11. Which structural formula(s) from above could have an isomer and still contain the same functional group?
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12. Draw the isomers for the structural formulas identified in #11.
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Date: ___________Right Now
Quick Notes:
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Polymer Structure and Property Date: ___________
Polymers are long molecules that contain a chain of repeating units. When a polymer is unmodified, the arrangement of covalent bonds in long, string like polymer molecules causes the molecules to coil loosely. In this form, the polymer is flexible and soft. We use polymers in many everyday products, such as bottles, Styrofoam, synthetic clothing and plastic bags.
We can change the properties of a polymer by adding molecules that act as internal lubricants among the polymer chains. One way to change a polymer’s properties is to form polymer chains perpendicular to the main chain, forming side chains. These polymers are called branched polymers. The extent of branching can be controlled by adjusting reaction conditions. Figures (a) and (b) in the diagram are branched.
Another way to alter the properties of polymers is through cross-linking which connects two straight chains. Polymer rigidity can be increased if the polymer chains are cross-linked so that they can no longer move or slide readily. You can see this for yourself if you compare the flexibility of a plastic soda bottle with that of its screw-on cap. Polymer cross-linking is much greater in the cap. Figures (c) and (d) in the diagram are cross-linked.
1. What is a polymer? What are some uses of polymers?
2. What’s the difference between branched-chain and cross-linked polymers?
3. If a pencil line represents a linear polymer, draw a collection of loosely coiled polymer molecules.
4. Draw at least two different models of branched-chain polymers.
5. Draw several linear polymer chains that have been cross-linked.
6. How do branching and cross-linking change the properties of a polymer?
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Date: ___________Right Now
Quick Notes:
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3C1&7 Reading Guide: Petrochemicals and Condensation Polymers Date: ___________
Compare addition polymers and condensation polymers in the chart below. Include structural formulas and reactions that produce these polymers.
Addition Polymers
Structural Formula:
Reaction that produces these polymers:
Other information:
Condensation Polymers
Structural Formula:
Reaction that produces these polymers:
Other information:
Similarities
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3B&C Review1. Classify each of the following as an example of kinetic energy or potential energy:
a. a basketball resting on the ground __________________________
b. a skier moving down a slope __________________________
c. a spinning fan __________________________
d. a candle prior to being burned __________________________
2. Explain the law of conservation of energy.
3. What is the difference between potential energy and kinetic energy?
4. Energy is not always completely converted from potential energy to a useable form of energy. Typically, what form does “lost energy” take?
5. What is the general equation for the complete combustion of a hydrocarbon?
6. Consider the reaction: CO + H2 + O2 → CO2 + H2O + 525 kJ.a. Is energy released or absorbed?
b. Classify this reaction as exothermic or endothermic.
c. Draw a temperature vs. time graph for the reaction. d. Draw a potential energy vs. time graph for the reaction.
7. In a laboratory activity, a student team measures the heat released by burning an unknown fuel source. Remember that the specific heat of water (C) is 4.18 J/g*oC.a. Calculate the amount of heat that the water absorbs.
b. How much heat does the fuel release?
c. What assumption do you make to answer part “b” above? What are weaknesses of that assumption?
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Mass of water: 188.5 g
Initial water temperature: 9.2 C
Final water temperature: 51.9 C
Mass of fuel burned: 0.725 g
8. Why is burning a candle an exothermic process even though we have to provide energy for it to start?
9. What are organic molecules?
10. You are familiar with petroleum’s use as an energy source. It is also used for “building.” What does this mean?
11. Polymers can be chemically altered to exhibit physical properties that are useful for a specific purpose. Cross-linking is one way that chemists alter the properties of a given polymer. What is cross-linking?
12. Compare a molecule containing four carbon atoms that represents an alcohol, a carboxylic acid, and an estera. alcohol b. carboxylic acid c. ester
13. Does each of the following pairs represent isomers or the same substance? Explain.Structural Formula 1 Structural Formula 2 Isomer or Same? Type of Compound
CH2=CH−CH2−CH3 CH3−CH2−CH=CH2
14. Draw picture of a polymer with and without cross-links.
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Formula:
Name:
Structural Formula:
Formula:
Name:
Structural Formula:
Formula:
Name:
Structural Formula:
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