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The purpose of the activities in this lab is to compare and contrast ethanol to fossil fuels. For each fuel, we will compare the amount of carbon dioxide produced, the amount of carbon soot produced and the amount of heat produced when burned.
Students who demonstrate understanding can:
Which Fuel Burns Cleaner?
Which Fuel Produces More Carbon Dioxide When Burned?
Which Fuel Burns the Hottest?
Students should wear safety goggles for each of the experiments. Use extreme caution when using an open flame and follow all fire safety guidelines. Students should know how to properly extinguish a flame as well as where the fire blanket and fire extinguishers are located. Students should not wear baggy or bulky clothing and long hair should be pulled back.
Length of Time for Preparation: 45 minutes Length of Time for Classroom Teaching: 2 class periods
Each activity will take 15-20 minutes to setup. Allow about 45 minutes to set up all three activates. Color the kerosene with one drop of food coloring to help students tell the difference between the two burners.
There are many claims that ethanol is cleaner burning, more energy efficient and better for our environment than burning fossil fuels. This lab is designed to compare ethanol and kerosene, a fossil fuel, to see if these claims are accurate.
Most energy used in the United States consists of burning a combustible material and harnessing the heat, or energy, produced. The burning of combustible materials releases harmful gases and soot into the air. Typically, fuels that produce more soot tend to be more harmful to the environment. About 50 percent of air pollutants come from transportation the burning of combustible fuels. Soot is the most visible form of air pollution and leaves a black coating on whatever it settles on. Also, when breathed in, the tiny particles can cause health problems. Carbon dioxide is a product of all carbon-based fuels when burned. Carbon dioxide is a greenhouse gas and plays a role in global warming. Environmental impacts can be measured by observing the particulate matter, or soot, released into the air and by measuring the amount of carbon dioxide produced.
Fuels that produce more heat per unit produce more energy. To determine efficiency, the heat released during the combustion process may be measured by heating a set volume of water. Students will collect both qualitative and quantitative data to compare the two fuel sources.
Introduce the topic and assess students for prior understanding.
Let students discuss their ideas, and guide the discussion without telling them if they are right or wrong.
This lab consists of three activities to compare ethanol and kerosene. Each activity can be done independently or collectively. Each activity can be done as a whole class demonstration or as lab stations. What you do and how you do it should be determined by your learning objectives and the needs of the students in the classroom.
Which Fuel Burns Cleaner? 1. Using a digital scale, find the mass of each of your two 250-mL beakers and record information on the data sheet. 2. Use two burners, one containing kerosene (blue) and one containing ethanol (clear). Make sure the wick of the burners is just barely above the metal casing. Light the burners and check to make sure the flame height is about 2-3 cm above the burner. Extinguish the flame and adjust the wick if necessary. 3. Set up two ring stands with clamps. Set an alcohol burner in front of each ring stand. Invert the 250-mL beakers and clamp them into place with the opening facing downward. Clamp the beakers directly over each burner, approximately 20 cm above the top of the burner. Make sure each beaker is at the same height. 4. Light each burner and start the timer. Let each fuel burn for 2 minutes. During this time, record any observations of what is happening as the fuels burn. 5. After 2 minutes, extinguish each flame. Give the beakers a couple of minutes to cool. Using a hot pad, or beaker tongs, carefully remove each beaker from its clamps. Set aside and make sure the beaker is completely cool before setting it on a digital scale. Use the digital scale to find the mass of each beaker and record the results. Subtract the final mass from the initial mass of each beaker to find the difference.
Questions
Which Fuel Produces More Carbon Dioxide When Burned? 1. Measure the carbon dioxide level of the classroom. Break off the ends of the gas detection tube. Insert the gas detection tube into the end of the tubing connected to your 100-mL syringe. There is an arrow indicating the direction of air flow on one side of the gas detection tube. The tubing goes on the end opposite of the arrow. Extract 100 mL of air from the room. This will take a couple of minutes. Pull back on the stopper as far as you can and hold. This creates a vacuum. Over time, this will fill with air. As this happens, you will be able to pull the stopper back further. Hold the stopper at the 100-mL mark until the stopper is no longer being pulled back into the syringe.
2. Read the carbon dioxide level of the classroom. Take your reading from where the solid purple band stops. There will be a gradient of lighter purple going further up the tube. The measurement is read from where the solid purple ends and the gradient begins. (Picture below read about 500 ppm.)
3. Break off the ends of another gas detection tube. Insert the gas detection tube into the end of the tubing connected to your 100-mL syringe. Set aside. 4. Burn a glass fuel burner of ethanol in the vent pipe for 2 minutes. 5. Extinguish the flame and cover the top of the vent pipe 6. Through the hole in the side of the pipe, insert the gas detection tube and extract 100 mL of air. Hold the stopper at the 100-mL mark until the stopper is no longer being pulled back into the syringe. 7. Read the carbon dioxide level. 8. Repeat the same procedure (steps 3-7) for the kerosene fuel. 9. Compare the carbon dioxide readings for all three tubes.
Which Fuel Burns the Hottest? 1. Give the students two burners, one containing kerosene (blue) and one containing ethanol (clear). Make sure the wick of the burners is just barely above the metal casing. Light the burners and check to make sure the flame height is about 2-3 cm above the burner. Extinguish the flame and adjust the wick if necessary.
2. Mass each burner and record the initial mass of each burner.
3. Use a graduated cylinder to measure and place 100 mL of room temperature water into the metal cup. (100 mL of water also has a mass of 100 g.)
4. Using a ring stand and ring clamp, position the cup 5 cm above the burner.
5. Use a clamp to suspend the thermometer in the water. The thermometer should not touch the bottom or side of the can. Measure and record the initial temperature of the water in the cup.
6. Light the burners and make sure the flame is centered under the cup. Set the timer for 5 minutes, then extinguish the flame. Measure and record the final temperature of the water.
7. Repeat this process for both fuels. Depending on the time you have in class, this can be done up to three times to develop an average. If you do this more than once, use room temperature water for each test and make sure to clean the soot off the bottom of the cup each time.
8. Find the mass of the burner and record that under the final mass.
During the 5-minute burn time, did the ethanol or kerosene use more fuel?
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Resources
To learn more about agriculture careers, visit https://agexplorer.ffa.org/.
Any educator electing to perform demonstrations is expected to follow NSTA Minimum Safety Practices and Regulations for Demonstrations, Experiments, and Workshops, which are available at https://static.nsta.org/pdfs/MinimumSafetyPracticesAndRegulations.pdf, as well as all school policies and rules and all state and federal laws, regulations, codes and professional standards. Educators are responsible for abiding appropriate legal standards and better professional practices under a duty of care to make laboratories and demonstrations in and out of the classroom as safe as possible. If in doubt, do not perform the demonstrations.
This lesson is the work product of the Kansas Corn Commission. Our lessons are written in collaboration with Kansas teachers for use in the classroom. Teachers may copy and share this curriculum. Use of this product for commercial or promotional use is prohibited without express permission of Kansas Corn.
As the need to produce more food with less resources grows, it is important that future generations have a better understanding of agriculture and how corn farming and agriculture fit into our daily lives. That’s why the Kansas Corn STEM program provides lessons to teach science through the lens of corn. We are committed to providing free materials and training to support educators.
