In this lab, students will learn about ethanol and its important role in our world’s ever increasing demand for energy. Students will go through the process of fermenting and distilling corn for ethanol production.
This lab has many variables that can affect ethanol production. The procedure can be followed as is, or a more inquiry-based lesson can be used by having students choose a variable and make changes to see how that variable affects the amount of ethanol produced.
Teachers should allow for an hour to gather materials and prepare the necessary solutions.
The increasing demand of fuel for transportation, increased world-demand for oil (gasoline), and the negative consequences of global warming have all contributed to the increased use of corn-based sugar to produce ethanol. Ethanol is blended with gasoline and burned in many of today’s passenger cars and trucks. Most gas stations currently use 10% ethanol in their gasoline. However, it has also been used as 85% ethanol to 15% gasoline at some gas pumps called, “E85” or flex fuel. Running this fuel in the gasoline motor typically does not require any mechanical modification. Not all gasoline motors are manufactured to run on E85, so it is best to check the vehicle owner’s manual before fueling up with E85.
Commercial production of fuel ethanol involves breaking down the starch present in corn into simple sugars like glucose and feeding these sugars to yeast for fermentation. Next, they recover ethanol, and other byproducts, such as animal feed, corn oil, and carbon dioxide. Ethanol is an alcohol produced by yeast during fermentation. Fuel ethanol is ethanol that has been highly concentrated and blended with gasoline to render the alcohol undrinkable.
For each pound of simple sugars, yeast can produce approximately 0.5 pounds (0.15 gallons) of ethanol and an equivalent amount of carbon dioxide. Corn is used for ethanol production because of its large volume of carbohydrates, specifically starch. Starch can be easily processed to break down into simple sugars, and fed to yeast to produce ethanol. Modern ethanol production can produce approximately 2.8 gallons to 3 gallons of fuel ethanol for every bushel of corn.
About 40% of the United States’ corn crop is used to produce ethanol. Ethanol production uses only the starch portion of the corn, which is about 70% of the kernel. All the remaining nutrients: protein, fat, minerals, and vitamins, are concentrated into distillers grains, and are used as feed for livestock. Some ethanol plants also remove the corn oil from distillers grains to create renewable diesel.
Possible topics could include:
Let students discuss their ideas, and guide the discussion without telling them if they are right or wrong.
Preparation of Enzymes (Prepare before the start of the lab)
Preparation of Corn Mash (1 to 2 class periods depending on schedules)
Optional Procedure for Overnight Fermentation
This procedure will allow you to track the CO2 production of the yeast. Knowing how much gas is produced will allow you to track how much fermentation has taken place and allow you to wait to distill until fermentation has stopped or significantly slowed (anywhere from 24 to 36 hours). (Note: See Teachers Tip)
Filtering the Solids (10-15 minutes)
Distillation of Ethanol from Corn Mash (1-2 hours depending on how long it takes your heating mantle to warm up. Plan to continue running after class has completed)
Use a pipet to remove a 2 ml sample of your distilled ethanol and place the ethanol on a watch glass or in a ceramic evaporating dish. Light the ethanol with a lighter. A quality sample will light with a pale blue flame. Time how long the flame burns. The longer the flame burns, the greater the alcohol concentration.
If the flame does not burn, the mixture may contain too much water.
Ethanol’s boiling point is 78.37°C and water’s is 100°C; therefore, it is important to keep the temperature between these two boiling points. If distillation ran with temperature close to 100°C, too much water may have gotten into the sample.
There are two possible solutions:
Potassium carbonate has saturated the water and forced the ethanol out of solution. The food coloring stays in the ethanol layer. This should be nearly pure ethanol.
This demonstration shows the flammability and potential stored within vaporized ethanol.
It is recommended to have at least two water bottles for this demonstration especially if you need to do this in back to back class periods. The demonstration cannot be performed again directly after it is completed. A small fan can be placed near the opening of bottle to help vent out the gas and circulate fresh air into the bottle between demonstrations.
It is recommended to have at least two water bottles for this demonstration especially if you need to do this in back to back class periods. The demonstration cannot be performed again directly after it is completed. a small fan can be placed near the opening of bottle to help vent out the gas and circulate fresh air into the bottle between demonstrations.
This Bio-Energy Fuel Cell Kit from Horizon allows you to convert ethanol directly to electricity without combustion. Dilute the 95% ethanol to a 10% solution. Put the ethanol into the reservoir. The fuel cell produces enough electricity to power the small fan. One of the byproducts of the reaction is acetic acid, which can be tested with pH paper . Refer to and follow directions that accompany the kit.
Reflection questions can be done as a whole class discussion, in small groups, or science journals/interactive notebooks.
These examples of questions that could be used to assess your students. Use whatever assessment method is appropriate for your students.
Ethanol is a part of the agricultural industry that has job openings from corn farming, ethanol production, to government policy jobs in Washington, D.C. Ethanol product jobs are readily available, and so are jobs in biofuel research. Typically, you do not need a degree to work in an ethanol production plant, but for higher salaries, consider a degree in agriculture, chemistry, biology, or a related field. Workers in ethanol plants transport the fermented corn to distillers, monitor the dehydration process, and package the final ethanol product safely. Car companies are increasingly advancing their research departments to deal with the growing trend of renewable energy. The government also hires workers for the research and development of ethanol products.
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 http://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.
Investing in teachers is a priority therefore the Kansas Corn Commission is committed to providing free materials and training to help teachers excel in the classroom. Distillation kits and funding for ethanol plant tours are available to teachers who teach Kansas Corn’s ethanol labs. Teachers who seek to expand their knowledge and skill of these labs are encouraged to seek out a training opportunity.