Marlene Lara The Coca Cola Secret Formula (DO NOT DRINK)

Questions & Answers:

1. In chemical kinetics, scientists figure out the rate of a chemical reaction. How would you determine the rate of the iodine-starch reaction?

We've learned that if we add more sodium sulfite to the iodine-starch reaction, the solution turns clear. When sodium sulfite runs out, we know that it reacts with iodate to make iodide and iodine molecules, eventually triiodide so that the blue/black color change occurs. Thus, the change in concentration of sulfite will be measured over the time (in seconds) to figure out the reaction rate. We can eliminate that the starch determines the reactant rate because iodine is what makes the starch turn blue/black. And even if we add more potassium iodate, the IO3- still needs to react with sulfite to make iodine.

2. How is figuring out the rate of a chemical reaction different than thermodynamics?

Thermodynamics is concerned with finding where the energy is being transferred. Thermodynamics does not indicate the rate of the the reaction. Chemists and engineers need to know the rate of a chemical reaction in order to have a precise reaction every single time. They need to be exact on the amount of concentration to generate a reaction at a desired time constraint.

Reaction rate is calculated using the formula rate = Δ[C]/Δt, where Δ[C] is the change in product concentration during time period Δt.

3. Why does iodate result in iodine and iodide? Triiodide?

The best way to understand how iodine converts to iodide and iodine is viewing the following balanced equation:

IO3- + 5I- + 6 H+ --> 3I2 + 3 H2O

Iodate is IO3-. Oxygen is more negative and the hydrogen are being attracted to the oxygen atom. I- is most likely looking to stabilize by getting one electron to have 8 total valence electrons. I- has to covalently bond with another I- molecule which equals I2. If there are no more I2 molecules then the remaining are I-. Iodine is part of a reactive group that readily take an electron. So, triiodide molecules are highly likely to be formed. It is formed by combining aqueous solutions of iodide salts and iodine

4. Where in the Coca Cola cup did the reaction begin? Top? Bottom? Center? Explain why.

If you look at the slow motion video, you can see that the black specks are sparsely distributed all over the solution. We know that there is no even distribution of iodate and starch which means the color change is not designated to one particular spot. Instead, the collision theory is observed when iodine molecules are bouncing around trying to react with starch, the bisulfite is being consumed, and the hydrogen ions are being attracted to the oxygen atoms. Particles are colliding in the mixture and since the reaction happened so suddenly, we know that the activation energy is little. The collision theory also explains that by increasing the energy, in which I made sure the starch and bisulfite were mixed in warm water, the reaction occurred faster because it took less time to dissolve them.

Applications to Everyday Life:

Gram positive bacteria

From a broader perspective, using iodine to detect starch is one of many types of tests to categorize biological and chemical substances. For example, iodine is used to detect gram positive bacteria. Gram positive bacteria adhere to the blue/purple dye and this determines what antibiotics you are prescribed. Gram positive bacteria are easier to kill and take a longer time for antibiotic resistance. If your infection is caused by a gram positive bacteria, you're most likely going to be prescribed penicillin.

Mashing

The iodine-starch complex is used in mashing. What is mashing? It is required for making beer. The grain starches are converted into fermentable sugars. The iodine test is used to test for starch to make sure that all the starch has converted into fermentable sugars.

Counterfeit Money Detector Pen

They are not elaborate but they can detect fake bills by creating a dark stain when the iodine solution reacts with the starch in wood-based paper. This is just meant for those that quickly print money and hope the cashier glances it and accepts it as real.

OxyClean Commercial

Have you ever seen the OxyClean commercial when a man has a big clear tub in front of him with a translucent whitish liquid and the "stain"? He swirls the mixture and the blue stain magically disappears. That blue stain is iodine and the translucent whitish liquid is some kind of salt, could actually be sodium sulfite! OxyClean in fact has sodium carbonate as an active ingredient and if we mix the black liquid with some OxyClean powder, it will remove the black color.

It's Black Magic!

Magicians and psychics would use this to cleanse somebody's body from evil thoughts. Thanks to chemical kinetics, people that experimented with this mixture can know exactly when the color would change. It can be delayed for a few seconds and even two minutes.

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