Science Smarts: Budding scientists, watch what happens right before your eyes

By Medicine Hat News Opinion on April 18, 2020.

I often get many requests for junior and senior high students and often neglect these budding scientists in my writing each week as the materials can often be a bit more complicated to get. I put myself up to the challenge and I think I have done it this week. I have come up with one of my favourite Chemistry experiments, and simplified it so you could do it at home with materials found right in your kitchen and bathroom cabinet. This is an amazing chemical reaction that happens right before your eyes. Let’s get started!

*Remember to ask an adult before doing this experiment.

Materials

3 clear glasses

water

corn starch

iodine

hydrogen peroxide

measuring spoons

measuring cups

safety glasses

Vitamin C tablets (100 mg total)

zipper baggie

masking tape (for labeling)

Procedure

1. Place your safety goggles on.

2. Label each of the three glasses: Vitamin C; Vitamin C and iodine; hydrogen peroxide and starch.

3. Take the Vitamin C tablets (1000 mg total) and place in the zipper baggie. Smash them up into a fine powder.

4. Measure 60 mL (1/4 cup) of warm water and place it in the cup marked “Vitamin C”. Add the crushed up Vitamin C tablet and stir well. Set aside for now.

5. In the Vitamin C and iodine cup, measure 60 mL (1/4 cup) of warm water. Add 5 mL (one teaspoon) of the vitamin C mixture AND 5 mL (one teaspoon) of iodine. Stir well and set aside.

6. Take the glass labelled hydrogen peroxide and starch. Measure and add 60 mL (1/4 cup) of warm water. Add 15 mL (one tablespoon) of hydrogen peroxide AND 2.5 mL (1/2 teaspoon) of cornstarch. Stir well.

7. Pour the cup labelled Vitamin C and iodine into the hydrogen peroxide and starch cup. Mix well.

8. Observe.

9. Once finished, dispose of all liquids down the drain and run some water after it.

What is going on?

This chemical reaction is a fairly common one known as “The Iodine Clock”. When you mix the solutions together, there are two chemical reactions occurring at the same time. The iodine reacts with the Vitamin C and the starch. As you observed, the iodine and Vitamin C create a clear liquid while the iodine and starch create a blue liquid. As soon as the Vitamin C is used up in this reaction, the iodine begins to react with the starch and a dark blue liquid emerges right before your eyes. You can control the amount of time between reactions by varying (increasing or decreasing) the amount of Vitamin C in the solution. Give it a try!

NEW: For great curriculum specific activities please visit our website at: http://praxismedhat.com/programs-resources .

Please note that because of the current health situation, our physical office is temporarily closed.  Praxis will not be distributing kits or offering other direct services for now. We will continue to do science outreach via our web page and social media.

Patty Rooks, Senior Scientific Consultant PRAXIS, “Connecting Science To The Community”. Contact Praxis at praxis@praxismh.ca, http://www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook.

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