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11 16 Unit 4 Lesson 5

Could any chemical reaction fuel a car?

QUESTION:  Can any chemical reaction be used to fuel a car? Do all chemical reactions ”release” energy? 

Learning Objectives:

  • Compare and contrast endothermic and exothermic reactions. 
  • Describe when heat is required and when heat is released in chemical reactions
  • Use experimental data to determine if a process is endothermic or exothermic

Warm-up:

  • Attendance 
  • Open Student IMT Unit 4, make sure the last lesson is updated. 
  • Write down the question for the day and complete the wonderings section for Lesson 5.  

IN-CLASS WORK:

  • Open L4.5 student sheet, make a copy, and save it to your drive. 
  • Review L4.5 and complete all parts of the IMT for lesson 5.

OUT-OF-CLASS WORK:

  • Open IMT for Unit 4 and make sure all sections for lesson 5 are complete. Make sure student sheet L4.5 is complete.
  • Complete check for understanding on L4.5

L4.5 Student Sheet

Lesson 4.5 Could any chemical reaction be used to fuel a car? Do all chemical reactions “release” energy?

PROCESSING LESSON 4 EXPERIMENT- EVAPORATION VS COMBUSTION OF ETHANOL:

  1. Which process resulted in the greatest mass loss? Evaporation created the greatest mass loss

  2. How does mass loss relate to the movement of particles?

  3. Complete the table for the evaporation vs combustion of ethanol. 

EVAPORATION COMBUSTION
Data including mass loss and key observations
Chemical equation with states
Particle model of ethanol in chamber
(BTB and CoCl2 strip are NOT included)
Where is the energy in the process?
  1. Briefly summarize three ways the combustion of ethanol is different than the process of evaporation.  Be sure to address energy as one of the ways.

1.

2.

3.

APPLYING RESULTS TO ENGINE MODEL

  1. How would you use this information to revise our working model to explain how fuel makes an engine work (and therefore a car move)? Keep in mind that ethanol is added to gasoline. Consider...

  2. Which stroke(s) involve the process of evaporation?

  3. State evidence from your everyday experiences that gasoline evaporates as well as the ethanol additives.

  4. Which stroke(s) involve combustion?

  5. In our model so far, how does fuel make an engine work (and therefore a car move)?

  1. Today’s question is ‘Can any chemical reaction fuel a car?’ List experiences with chemical reactions in your day to day activities and think about whether a reaction like you describe could power a car.

DEMO - TWO SALTS IN A ZIPLOC BAG

Ba(OH)2·8H2O(s)  +  NH4Cl(s)  →  BaCl2·2(H2O)(s)  +  2NH3(aq)  +  8H2O(l)

  1. Look at the following balanced equation. What information does this equation give you? 

  2. After observing this reaction, what information can you add?  reaction was endothermic and makes the bag feel cold to the touch.

  3. In which direction did heat move in this reaction?  From your hand to the reaction, the heat is moving into the bag.

INVESTIGATING ENERGY IN OTHER PROCESSES

Materials

  • 3-Thermometers -

  • 1-Ring Stand -

  • 1-Thermometer clamps

  • 1-Buret clamp

  • 3-150 mL beakers

  • 100 mL graduated cylinder

  • 250 mL beaker for distilled water

  • Ammonium nitrate, NH4NO3

  • Calcium chloride, CaCl2

  • 3-Stirring rods

  • Scale, spatula, 2-weighing boats

  • Stop watch/timer

Safety

  • Wear safety glasses at all times to protect your eyes from chemical spills or splashes.

  • Handle substances with care. Do not ingest any of the substances.

Procedure

  1. Set up a ring stand with three clamps, and attach one thermometer to each of the clamps.

  2. Obtain approximately 500 mL of water from the white carboy container at the sink, if your instructor has not done this for you.

  3. Label your beakers: #1 ,#2, #3, if not done so for you.

  4. Fill 3-150 mL beakers with 50 mL of water each using a graduated cylinder. Record the exact volume of water used for each in the data table.

  5. Place the beaker so that the thermometer is immersed in the water but not touching the bottom or the sides of the beakers.

  6. Record the initial temperature of the water in each of the beakers in the data table.

  7. Using the scale and a weighing boat, measure approximately 4.0 g of ammonium nitrate.  Record your exact mass in the data table. 

  8. Using the scale and a weighing boat, measure approximately 4.0 g of calcium chloride.  Record your exact mass in the data table.

  9. Simultaneously, add the 4.0 g of ammonium nitrate to one beaker, and add 4.0 g of calcium chloride to the second beaker, and leave the third beaker without any chemical added.

  10. Immediately start the stop watches and stir the beakers with a stirring rod continuously. 

  11. Record the temperature every minute for a total of 10 minutes in the data table.

  12. Clean by emptying the solutions into the waste beakers in the fume hood. Rinse the beakers, stirring rods, and thermometers with water. 

  13. Return everything as it was before beginning the experiment including placing materials especially the chemicals on the red tray. 

Data

Mass and Volume Measurements

Beaker Number Substance Volume of H2O (mL) Mass (g) of solute
1 Ammonium Nitrate 50ml 4.37g
2 Calcium Chloride 50ml 4.2
3 Water Only 50ml n/a

Solution Temperature Measurements

Ammonium Nitrate Calcium Chloride Water Alone
Time(min) Temp(ºC) Time(min) Temp(ºC) Time(min) Temp(ºC)
0 12.6 0 24.7 0 18.6
1 13 1 24.5 1 18.7
2 13.5 2 24.4 2 18.8
3 14.0 3 24.1 3 18.9
4 14.0 4 23.8 4 18.9
5 14.4 5 23.8 5 19.0
6 14.6 6 23.8 6 19.1
7 14.8 7 23.7 7 19.1

RESULTS/ANALYSIS

  1. For each substance, look at the data table and record the highest temperature and lowest temperature.
Substances Highest temperature (ºC) Lowest temperature(ºC)
Ammonium Nitrate 14.8 12.6
Calcium Chloride 24.7 23.7
Water 19.1 18.6

  1. a)  An exothermic process or reaction releases energy. Which solution released heat or was “exothermic”?

    b) An endothermic process or reaction requires energy. Which solution required heat or was “endothermic”?

  2. Aqueous (aq) is used by scientists to indicate that a solid is dissolved in water. Equations can be used to describe the process of dissolving each of these compounds.  Modify the equations so that heat is shown as part of the equation. Do this by adding heat (+ heat) to either the reactant or product side of the equation.  

    Dissolving NH4NO3 in H2O: NH4NO3 (s) → NH4NO3 (aq)  Dissolving CaCl2 in H2O: CaCl2 (s) → CaCl2 (aq)

  3. These processes are used in our lives as hot packs and cold packs.  

  4. Which chemical would you use in a cold pack?  Why?

  5. Which chemical would you use in a hot pack?  Why?

  6. This investigation helped us define the flow of energy of a system. Do you think either of these processes could be used as energy for moving a car? Explain your answer.

  7. If we are looking to find alternative fuel sources, what are some criteria they should meet to power the engines we currently use?

NEXT STEPS:

  1. Reflect on today’s question: Could any chemical reaction be used to fuel a car? Do all chemical reactions “release” energy?

  2. Open up the IMT for this unit, complete all boxes for lesson 5

  3. Make sure all parts of the L4.5 student sheet are complete & complete the check for understanding on schoology. 

REVIEW & REINFORCE:

Use the following sections of the textbook to help you review materials that were covered in this lesson

Last update: June 5, 2023
Created: June 5, 2023