AUTHOR'S NAME:  Katie Larsen

 

TITLE OF LESSON:  Solvents:  Making Ethanol from Molasses

 

TECHNOLOGY LESSON:  No.

 

DATE OF LESSON:  September 29, 2006

 

LENGTH OF LESSON:  Two 50 minute lessons (spaced a few days apart)

 

NAME OF COURSE:  Chemistry

 

GRADE LEVEL:  11th Grade

 

HONORS, REGULAR, OR MAGNET:  Any

 

SOURCE OF THE LESSON: 

 

GEMs:  Green Education Materials

“Biosynthesis of Ethanol from Molasses”

http://greenchem.uoregon.edu/gems.html

 

TEKS ADDRESSED:

Chapter 112.45 Chemistry (c)  Knowledge and skills.

(1)  Scientific processes. The student, for at least 40% of instructional time, conducts field and laboratory investigations using safe, environmentally appropriate, and ethical practices. The student is expected to:

(A)  demonstrate safe practices during field and laboratory investigations; and

(B)  make wise choices in the use and conservation of resources and the disposal or recycling of materials.

(2)  Scientific processes. The student uses scientific methods during field and laboratory investigations. The student is expected to:

(A)  plan and implement investigative procedures including asking questions, formulating testable hypotheses, and selecting equipment and technology;

(B)  collect data and make measurements with precision;

(C)  express and manipulate chemical quantities using scientific conventions and mathematical procedures such as dimensional analysis, scientific notation, and significant figures;

(D)  organize, analyze, evaluate, make inferences, and predict trends from data; and

(E)  communicate valid conclusions.

(12)  Science concepts. The student knows the factors that influence the solubility of solutes in a solvent. The student is expected to:

(A)  demonstrate and explain effects of temperature and the nature of solid solutes on the solubility of solids;

(B)  develop general rules for solubility through investigations with aqueous solutions; and

(C)  evaluate the significance of water as a solvent in living organisms and in the environment.

  

CONCEPT(S):

“Making Ethanol from Molasses” reveals to students that the same solvent (in this case ethanol) can come from different sources, and that the solvent’s production is just as important to consider as the solvent’s properties when determining impact on the environment.  This lesson focuses on ethanol as a solvent, its uses and the two main ways to produce it (petroleum vs. yeast).

 

PERFORMANCE OR LEARNER OUTCOMES:

Students will be able to:

 

RESOURCES, MATERIAL AND SUPPLIES NEEDED:

For each student group:

70 ml of molasses

70 ml of water

250 ml Erlenmeyer flask

0.5 grams of yeast

Rubber stopper for flask

Bent glass tube 9for rubber stopper)

Rubber hose

Straight glass tube

Limewater

250 ml round bottom flask

Heat plate

 

SAFETY CONSIDERATIONS: 

Care with handling glassware, hot plate and ethanol.  Goggles must be worn.   

 

SUPPLEMENTARY MATERIALS, HANDOUTS: 

 

None. 

 

 

 

 

 

 

FIVE E TEMPLATE

 

Time

Teacher Does

Probing Questions

Student Response

10 min

/ day

ENGAGE

 

First Day

The teacher hands out packets of bread yeast to each student as they walk into the room. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Second Day (a few days later):

The teacher asks students to pull out the ethanol they made and initiates discussion about the process of making it. 

 

 

First Day
What are some solvents that we know? 

 

How do we know those chemicals are solvents (in other words, what makes a chemical a solvent?)

 

What can we use solvents for?

 

How are some of the solvents (on the list generated by the students) made?

 

Could I make any of these solvents from yeast? 

 

Second Day:

Did you feel safe making the ethanol this way?

 

What were your observations? 

 

 

 

 

Varies.  The students may be perplexed about how yeast could help with the production of solvents, or they may not be surprised.  

The Evaluate is to determine student familiarity with solvents during class discussion. 

40 min

EXPLORE

 

Students form groups of two to three students each. 

 

Students are asked the first three questions, and must find the answer using a biology textbook (or their own memory). 

 

After this questioning period, students begin work producing ethanol.

 

 

 

 

What are the waste products of yeast? 

 

What do yeast consume?

 

So what could we give to yeast and what would yeast give to us?

 

Can alcohol be used as a solvent?  If yes, why and how?

 

 

 

 

So how could we design a process that gives yeast sugar and we get the alcohol solvent?

 

 

 

 Alcohol

 

 

Sugars

 

 

Sugar, alcohol

 

 

 

Yes.  It is miscible with water and other organic solutes.  Ethanol can participate in hydrogen bonding. 

 

 

Varies.  Students may consider distillation (which is the planner process).  Creative ideas with some feasibility may also be pursued.

For the Evaluate, student’s lab reports will be checked to insure appropriate experimental procedure and understanding of process. 

25

min

EXPLAIN

 

The teacher hands out materials or gives students time on the internet to research how ethanol is made using petroleum. 

 

The teacher has the students compare the process to make ethanol from molasses with the process to make ethanol from petroleum. 

 

The teacher summarizes the lesson, with student input, by stating that the same solvent can come from different sources, and that the solvent’s production is just as important to consider as the solvent’s properties.  

 

 

 

Why is the petroleum process used to make ethanol?  What are the benefits?

 

What are the benefits of using sugar instead of petroleum as source of ethanol?

 

How is ethanol used as a solvent in industry? 

 

What are the solutes in the ethanol in those products (perfumes, paints, etc)?

 

 

Cost.  Well-established industry, etc.

 

 

 

Avoids most of the pollution problems associated with the petroleum industry. 

 

Cleaning, perfumes, paints, beverages and tinctures.

The Evaluate is to have students provide a summary of their comparison of the two different processes and what the solvent is used for. 

15

min

EXTEND

Two extensions are possible:

 

First:  Another important “green” solvent for industry, including the coffee industry, is supercritical CO2.  The students will research how supercritical CO2 is made and evaluate its use as a solvent, using green chemistry principles. 


Second:  Use ethanol for an experiment requiring its use as a solvent.

 

For industries that have switched to supercritical CO2 as a solvent, why did they make the change? (In other words, what are the benefits of using supercritical CO2).

 

How is supercritical CO2 made or retrieved?  Are there different ways of making it?

 

Why are solvents used for cleaning?

 

 

 

 

 

EVALUATE

 

 

Occurs throughout the lesson.