GK12 Oxidation-Reduction and Vitamin C
Topic:
Oxidation-Reduction Reactions using the Biologically Important Molecule Ascorbic Acid
National Science Education Standards:
Life Science - CONTENT STANDARD C: As a result of their activities in grades 9-12,
all students should develop understanding of
 Matter, energy, and organization in living systems
Science as Inquiry - CONTENT STANDARD A: As a result of activities in grades 9-12,
all students should develop
 Abilities necessary to do scientific inquiry
 Understandings about scientific inquiry
MS Science Frameworks:
Life Science Biology II 1. Apply inquiry-based and problem-solving processes and
skills to scientific investigations.
c. Demonstrate the use of scientific inquiry and methods to formulate, conduct,
and evaluate laboratory investigations (e.g., hypotheses, experimental
design, observations, data analyses, interpretations, theory development).
Life Science Biology II 2. Describe and contrast the structures, functions, and
chemical processes of the cell.
d. Oxidation and reduction reactions
Objectives:
 Students will define oxidation and reduction reactions.
 Students will explain the relevance and importance of the biologically
important molecule ascorbic acid.
 Students will identify food sources of ascorbic acid.
 Students will make observations of oxidation in naturally occurring
substances.
 Students will conduct experimentation using copper (II) sulfate and
ascorbic acid.
 Students will make observations in experimentation using copper (II)
sulfate and ascorbic acid.
 Students will summarize the results of their analysis of oxidation-reduction
using copper (II) sulfate and ascorbic acid.
Classroom Procedure:
Engage (Time: 15 min)
Divide the students into groups of two. Pass activity sheets to each group. Discuss the
nutritional labels and the major vitamins found in orange juice. Ask students what they
know about vitamins and their functions. Pass out slices of oranges, lemons, and other
food substances that contain ascorbic acid that students may eat while discussing
functions of vitamins. Have students define oxidation and reduction reactions from their
textbook. Be sure each group has completed activity one of sheets provided.
Explore (Time: 15 min)
Show the students slices of apples that have been allowed to sit at room temperature
for 1 day with half of the apples sprayed with lemon juice and half of the apples without
lemon juice. Students will make observations and compare any differences noted
between the apples in lemon juice and apples without lemon juice. Using what they
know, ask students if they have any idea of what may be occurring with the apples and
allow them to record it on the activity sheet provided.
Explain (Time: 25 min)
Using power point, discuss the following topics: oxidation and reduction reactions,
water soluble vitamins, water insoluble vitamins, sources of vitamin C, vitamin C as a
biologically important molecule, and the importance of vitamin C for living things.
Demonstrate the transfer of electrons in oxidation and reduction reactions and
how anti-oxidants work.
Elaborate (Time: 25 min)
Students will conduct the experiment using copper (II) sulfate and ascorbic acid. Allow
students to complete questions on the activity sheet with their partner. Assist as
necessary.
Evaluate (Time: 10 min)
Discuss the answers to the lab questions as a class. Students will turn in completed
activity sheet.
Materials needed:
1. Ask students to bring in orange juice labels a few days prior to lessons or
print an orange juice label from the internet.
2. Bring enough oranges or other food sources of vitamin C for students to
eat and observe.
3. Sliced apples and lemon juice or lemons for exploration. Be sure to slice
apples in advance of class time so apples without lemon juice will have
time to oxidize.
4. Make copies of activity sheets for each student.
5. DEMONSTRATION>>>>>>
6. Prepare or purchase copper (II) sulfate solution for experiment.
7. Prepare ascorbic acid solution for experiment.
8. Set up lab for experiment.
Name ______________________
Oxidation-Reduction Reactions using the
Biologically Important Molecule Ascorbic Acid
Activity 1
1. With your partner, review the nutrition label.
What product is the nutritional label for?
________________________________________
What is the major ingredient found in
the substance?
________________________________________
What is the major vitamin(s) found in the
substance?
________________________________________
_________________________________________
2. Define oxidation reactions using your textbook.
3. Define reduction reactions using your textbook.
Activity 2
1. Write down your observations for each set of apples below.
Plain apples
Apples with lemon
juice
Observations
2. What do you think is occurring in each set of apples?
Plain apples
Apples with lemon juice
Activity 3
1. Draw and summarize the demonstration of oxidation and reduction
reactions.
2. Explain the function of anti-oxidan
Activity 4
Copper (II) Sulfate/Ascorbic Acid Lab
Materials:
Cu(II)SO4
Ascorbic Acid
2 beakers
Water
Disposable pipettes
1. Dissolve 1 gram of Cu(II)SO4 into 10 mL of water in a beaker.
2. In another beaker, dissolve 0.5 g ascorbic acid (vitamin C) in 5-10 mL of
water.
3. Add vitamin C solution dropwise to the blue Cu(II)SO4 solution with a
disposable pipet.
4. Note observations after each drop.
Name ______________________
Vitamin C
1. Hypothesis:
Cu(II)SO4?
What will happen when Vitamin C is added to
2. What is visually happening? What are your observations
during the demonstration?
3. Why does the color change?
4. What is occurring on a molecular level for the color to change?
5. Give a biological example this relates to. Draw a reaction
scheme.