Iodine Clock Assignment

The Iodine Clock (Chemical Change)

Throughout the "Iodine Clock" assignment, you will fill in the Iodine Clock Summary Table.

See some completed sample Iodine Clock Summary Tables

Part 1: The Iodine Clock

Watch the Iodine Clock Experiment on YouTube for students. (Optional: Watch the Experiment on YouTube for teachers.) Then conduct the "Iodine Clock" experiment.

Fill in the Iodine Clock Summary Table.

Part 2: Bill Nye Chemical Reactions

Watch Bill Nye Chemical Reactions (season 2 episode 1)

Complete the Bill Nye Chemical Reactions Worksheet

Fill in the Iodine Clock Summary Table.

Part 3: Kaboom Movie

Watch the Kaboom Movie.

Fill in the Kaboom Movie Worksheet.

Fill in the Iodine Clock Summary Table.

Part 4: The 100 mL Challenge

Students know that vinegar and baking soda create a fizzy chemical reaction when they are mixed. Students are trying to engineer a chemical reaction and regulate it so it only reacts up to a certain amount. They decide that they can regulate the size of the reaction by regulating the amount of baking soda they add to the vinegar.

Question: What is the effect of the amount of baking soda (1/4 tsp, 1/2 tsp, 3/4 tsp) on a chemical reaction’s rise toward the 100 mL line of a graduated cylinder?

Controlled Variables: Use 10 mL of vinegar for all reactions. Use 6 drops of liquid soap in the bottom of the graduated cylinder to slow down the reaction.

Complete the 100 mL Challenge Lab Sheet or do the inquiry steps in your journal.

Fill in the Iodine Clock Summary Table.

Lab Activity Reference: Inquiry In Action chapter 5

Part 5: Marshmallow Roast

Roast marshmallows over a candle and try to achieve physical change and chemical change, then identify which type of change is which. Gloves and safety goggles are required as you hold marshmallows with tongs over a candle placed on aluminum foil.

Fill in your Marshmallow Roast Lab Sheet

Fill in the Iodine Clock Summary Table.

Part 6: Endothermic Reaction

Chemical reactions can absorb or give off heat. Experiment with how adding different amounts of chemicals (baking soda and calcium chloride) to solutions (vinegar and water) makes the temperature fall and rise different amounts.

Endothermic Question: What is the effect of the amount of baking soda (1/4 tsp, 1/2 tsp, 3/4 tsp) on the temperature change when the baking soda is added to 10 mL of vinegar in an insulated cup?

Complete the Exo and Endothermic Reactions Investigation Sheet or do the inquiry steps for both investigations in your journal.

Fill in the Iodine Clock Summary Table.

Part 7: Exothermic Reaction

Exothermic Question: What is the effect of the amount of calcium chloride (1/4 tsp, 1/2 tsp, 3/4 tsp) on the temperature change when the calcium chloride is added to 10 mL of water in an insulated cup?

Complete the Exo and Endothermic Reactions Investigation Sheet or do the inquiry steps for both investigations in your journal.

Fill in the Iodine Clock Summary Table.

Lab Activity Reference: Inquiry In Action 5.4 and 5.6

Part 8: Acid/Base Lab

Use the color changes of red cabbage indicator to classify substances as acid or base. Then, use your knowledge of color changes to make a chemical change to (neutralize) an acidic solution with a base and vice versa.

Watch the Acid and Base Slide Show.

1. Carefully pour 2 tablespoons of indicator solution into each empty cup and place the four labeled cups on a white piece of paper.

2. Add 1/4 tsp. of cream of tartar to the proper cup and gently swirl to mix (then wipe the teaspoon clean).

3. Record data (color diagram and words) in the "Evidence Before" section of your Acid/Base Lab Sheet.

4. Repeat steps 2-3 with 1/4 tsp. of laundry detergent and 1 drop of vinegar.

5. Add a tiny amount (less than 1/4 tsp) of laundry detergent to the indicator + cream of tartar and swirl. Observe the color. If needed, continue this process until the solution returns to blue (then wipe the teaspoon clean).

6. Fill in the next two columns of your Acid/Base Lab Sheet.

7. Repeat steps 5-6 with a tiny amount (less than 1/4 tsp) of cream of tartar and then drops of vinegar

While completing the acid / base lab activity, fill in your Acid/Base Lab Sheet

Fill in the Iodine Clock Summary Table.

Lab Activity Reference: Inquiry In Action 5.7 and 5.8

Part 9: Precipitate

Formation of a precipitate is an indicator of a chemical reaction.

Follow the directions on and complete the Precipitate Lab Sheet.

Fill in the Iodine Clock Summary Table.

Part 10: Chemical Reaction Mat

Use the characteristic set of reactions for each of five powders to identify an unknown powder.

Procedure

• 1. Use a popsicle stick to place 4 equal piles of baking soda on the labeled laminated strip.

  2. Put 5 drops each of of water, vinegar, iodine and pH indicator on the different piles.

  3. Draw a color diagram with labels on your Reaction Mat Lab Sheet.

  4. Repeat steps 1-3 with the baking powder, cream of tartar, detergent, cornstarch and then unknown.

Complete the Reaction Mat Lab paper and Iodine Clock Summary Table.