CHEM 1030L – Fundamentals of Chemistry Laboratory
An Experimental Design and Investigation
Kudzu Labs: From Biomass to Biofuel
Note: Be sure to review the Experimental Design Overview presented in Week 1 to
remember what will happen during lab each week during this 3-week experiment.
Overview for Week 3 – Glucose Measurement and Evaluation of Hypotheses: Students will
measure the amount of glucose produced by each experimental mixture to determine which
pretreatment was best at breaking down plant cell walls. Students will also compare their
(1) hypotheses from Week 1 with
(2) results from Week 3
to determine whether the hypotheses were correct or incorrect. Finally, students will describe
additional experiments that could be performed to further investigate new ways of breaking down
plant cell walls to enable the production of glucose from kudzu.
Desired Outcomes of Week 3: Glucose concentrations measured, best pretreatment or pretreatments
identified, hypotheses from Week 1 reviewed.
Procedure for Week 3 – Measurement of Glucose
1. Recover the eight test tubes from the first lab.
2. Record appearance, including color, of each experimental mixture on the datasheet. Record any
observed differences from Week 2.
3. Measure pH: Using pH paper, determine the relative pH for each test tube. A simple method is to use a
clean stirring rod. Dip the stirring rod in the test tube and then place a drop of the solution onto the pH
paper. Rinse the stirring rod with distilled water after use in each test tube to avoid contamination.
Compare the moistened pH paper to the color scale on the pH paper container to determine the pH for the
solutions in each test tube. Record the pH for each test tube on the datasheet.
4. Record glucose concentration: Carefully read the package directions for the glucose test strips.
Practice using the glucose test strips by dipping one into the standard glucose solution. Allow the
moistened glucose test strip to rest for the time specified on the package and then read the results by
comparing the color of the test strip to the color chart on the package. The reading should match the
concentration listed on the glucose solution container. To measure the glucose in each test tube, begin by
shaking each test tube before dipping the test strip. Wait for the appropriate amount of time and record
the glucose concentration. Be sure to keep track of which test strip goes with which test tube. When all
test tubes have been measured, enter the glucose levels from Week 2 and Week 3 on the instructor's
computer.
5. Clean-up: When glucose levels have been tested in all test tubes and the results have been entered in the
student's datasheet and the instructor's datasheet, discard the test tube contents in the designated waste
containers and wash the test tubes with soap and water and rinse with distilled water. Return test tubes
that did not come from the lab station drawer to the boxes on the back bench.
Revised 4/12/2015 – T. Ekman
6. Data Analysis
a. The lab instructor will lead a discussion of the significance of the glucose levels found in the
blank (zero control) and the positive controls. The results from the control test tubes may
influence the interpretation of the data that result from the experimental test tubes (# 1-8).
b. Students will subtract the average "blank" from the Uncorrected Glucose Concentration for each
test tube and place the result in the "Corrected Glucose Concentration" column of the lab report
sheet.
Questions for Lab Report:
The instructor will announce how students should respond to the following questions.
Results for the blank
(a) What glucose response was found for test tube # 9, the blank?
(b) What did that indicate about the enzyme solution?
(c) How was that information used in determining the glucose concentrations of the remaining test
tubes?
Results for the positive controls
(a) What glucose response was found for test tubes # 10 & 11, the positive controls?
(b) What did that indicate about the enzyme solution?
(c) How was that information used in understanding the glucose concentrations of test tubes 1-8?
Experiment 1: Compare Test Tubes 1 & 2
(a) List the factors that were controlled.
(b) List the factor that was the variable.
(c) What was the glucose concentration in Test Tube 1?
(d) What was the glucose concentration in Test Tube 2?
(e) What effect did the variable (name the variable in your response) have on the amount of glucose
produced from the kudzu?
(f) Should the variable (name the variable in your response) be used as a pretreatment when trying to
break the kudzu down into glucose? Explain why or why not.
Experiment 1: Compare Test Tubes 1 & 3
(a) List the factors that were controlled.
(b) List the factor that was the variable.
(c) What was the glucose concentration in Test Tube 1?
(d) What was the glucose concentration in Test Tube 3?
(e) What effect did the variable (name the variable in your response) have on the amount of glucose
produced from the kudzu?
(f) Should the variable (name the variable in your response) be used as a pretreatment when trying to
break the kudzu down into glucose? Explain why or why not.
Experiment 1: Compare Test Tubes 1 & 5
(a) List the factors that were controlled.
(b) List the factor that was the variable.
(c) Experiment 1: What was the glucose concentration in Test Tube 1?
(d) What was the glucose concentration in Test Tube 5?
Revised 4/12/2015 – T. Ekman
(e) What effect did the variable (name the variable in your response) have on the amount of glucose
produced from the kudzu?
(f) Should the variable (name the variable in your response) be used as a pretreatment when trying to
break the kudzu down into glucose? Explain why or why not.
Experiment 1: Compare Test Tubes 1 & 7
(a) List the factors that were controlled.
(b) List the factor that was the variable.
(c) What was the glucose concentration in Test Tube 1?
(d) What was the glucose concentration in Test Tube 7?
(e) What effect did the variable (name the variable in your response) have on the amount of glucose
produced from the kudzu?
(f) Should the variable (name the variable in your response) be used as a pretreatment when trying to
break the kudzu down into glucose? Explain why or why not.
Heat Pretreatment - Four of the samples will be heated in hot water for 15 minutes and then cooled to room
temperature.
(a) Will heating the kudzu affect how well the plant cell walls will be broken down and, as a result, how
much glucose will be produced? If so, how and why?
(b) Restate your hypothesis from Week 1.
(c) Did your results from Week 3 confirm or refute your hypothesis? Explain how/why your hypothesis
was confirmed or refuted.
Chemical Pretreatment - Several of the samples will be treated with one of three chemical pretreatments.
(a) Which chemical (H2SO4, HCl or KOH) will provide the largest chemical impact in breaking down
the cell wall? How and why?
(b) Restate your hypothesis from Week 1.
(c) Did your results from Week 3 confirm or refute your hypothesis? Explain how/why your hypothesis
was confirmed or refuted.
What is the carbohydrate unit that comprises the polysaccharide cellulose?
How does cellulose differ from starch, which is made of the same carbohydrate unit?
Why is it, via chemical digestion, that humans can break down starch but not cellulose?
Can cellulose provide calories in the human diet? Does it provide any other nutritional value?
Revised 4/12/2015 – T. Ekman