Help Needed on "Investigate the Kinetics of the Color Changing Iodine Clock Reaction" Project

[biologymadcow]

Hi, I am following the procedures in the article which says to microwave cornstarch to form a starch solution needed for the reaction. During a test run, I forgot to microwave the cornstarch but the reaction seemed to continue without causing any problems. What is the effect of microwaving the cornstarch (and bringing it close to boiling), and does it make a difference if you don't microwave it?
https://www.sciencebuddies.org/science- ... n-kinetics

Also, does it matter what type of starch is used? I used potato starch instead of corn starch in my test run as well, and it also seemed fine.
Thanks.

[morgea]

Hello!

Microwaving cornstarch leads to the starch granules swelling and smoothening. Doing this allows the starch to absorb water well and dissolve faster. In the case of what occurred during your experiment, other factors may have impacted why the reaction continued without microwaving. The requirements for microwaving may depend on the concentration of the starch solution and the sensitivity of the response, leading to the action of microwaving not being necessary.

I do believe that the type of starch used. Although potato starch and corn starch are still carbohydrate polymers, different chemical differences could contribute to the results you got. Potato starch has a lower gelatinization temperature than cornstarch, which can thicken liquids faster. This is probably why you got the same results in the experiment without microwaving.

I hope this helps!