Sweet Solutions for Science on a Shoestring, Part 2

Heather Haley
Product Developer

As discussed in our previous Carolina Tips® article “Sweet Solutions for Science on a Shoestring, Part 1,” teaching science on a tight budget often requires creative use of common household items. Here’s another activity that utilizes an inexpensive everyday product—powdered drink mix.

Activity 3: Why No Metal Containers?

Topics covered: properties of acids, pH, kinetics, oxidation-reduction, consumer chemistry

Safety

Put on gloves. Steel wool can cut hands and should be handled with gloves. Emphasize that students should not eat, drink, or chew gum during activities performed in their science classroom.

Materials (per class)

Large Plastic or Glass Container (2 L or larger, item #721445)
Unsweetened Powdered Drink Mix (such as Kool-Aid®; Note: Must contain FD&C Red 40, Yellow 5, or Yellow 6)
Long-Handled Spoon
Electronic Balance (readable to 0.1 g, item #702357)

Materials (per group)

4 Clear Containers (150 mL or larger; item #721208, item #971170, or similar)
3 Wooden Stir Sticks (item #971319)
Graduated Cylinder, 100 mL (item #721618)
Coarse Steel Wool, 2 g (grade #3)
Fine Steel Wool, 2 g (grade #0)
Super Fine Steel Wool, 2 g (grade #0000)
Protective Gloves (item #706337 or similar)
Paper Towels (item #633954)
Stopwatch (item #962106)
Hot Tap Water
Permanent Marker

Teacher preparation

Prepare an unsweetened drink solution in a large plastic or glass container.
1. Pour the contents of unsweetened powdered drink mix into the container. No sugar is required for this activity.
2. Add 2 qt (1,893 mL) of tap water to the container containing drink powder.
3. Use a long-handled spoon to stir the contents of the container until all powdered drink mix dissolves.
(Optional) If the unsweetened drink solution will not be used right away, use a cover to seal the container. If necessary, the solution can be stored in the covered container for a week or more.
(Optional) Prepare 2-g samples of each type of steel wool for student use. Alternatively, students may divide steel wool into 2-g pieces.
1. Put on gloves. Steel wool can cut hands and should be handled with gloves.
2. Use an electronic balance to measure out 2 g of coarse steel wool and set aside.
3. Continue measuring out enough coarse steel wool for all student groups.
4. Measure out enough 2-g pieces of fine steel wool for all student groups.
5. Measure out enough 2-g pieces of super fine steel wool for all student groups.

Student procedure

Use permanent marker to label 4 containers “control,” “coarse,” “fine,” and “super fine,” respectively.
Add 50 mL of unsweetened drink solution to each of the 4 labeled containers.
Record observations about the appearance of each drink solution.
While wearing gloves, rinse each 2-g sample of steel wool in hot water. Hot water will remove some of the oil that prevents steel wool from rusting. Remove excess water from the steel wool by placing the sample in a paper towel and squeezing it. Discard the paper towel.
Use gloved hands to pull the steel wool fibers apart. Record observations about the appearance of each steel wool sample.
Use gloved hands to completely submerge a piece of coarse steel wool in appropriately labeled container.
Repeat the preceding step for fine and super fine steel wool.
Every 5 minutes, observe the appearance of the liquid and steel wool in each container by using a stir stick to lift the steel wool out of the container. Note the time elapsed when chemical reactions appear to cease.

Extension activities

Have students test how different colors of powdered drink mix are affected by steel wool. Azo dyes (Red 40, Yellow 5, Yellow 6, etc.) become colorless when reduced (like those created when citric acid reacts with iron in steel wool). Blue 1 is not an azo dye and does not change as dramatically. A purple drink solution that contains both Red 40 and Blue 1 will lose the red color and not the blue. The solution will turn blue instead of colorless.
Ask students to predict what will happen to beverages stored in aluminum containers. Brainstorm methods for preventing redox reactions between the aluminum can and the contents inside. Many aluminum cans have a thin layer of unreactive plastic lining the interior. The plastic liner prevents acidic beverages from reacting with the aluminum container and ensures that the can contents maintain appropriate colors and flavors.