If I put 1/2 of coco krips in 1 bag 1/2 of Frosted Flakes is another bag and 1/2 of Cheerios use that for the following sentences. If I had 1 cup of warm water to each bag, then add two tsp of yeast of each bag, then carefully compress all the air out of the bags and seal the bags tightly. Gently shake/squish the bag so that all the contents mix. Then allow the bag to rest for 15 minutes. What chemical reaction would happen inside each bag

In each bag, you would create an environment conducive to fermentation due to the combination of warm water, sugar, and yeast. Here's what happens step by step:

1. **Ingredients Breakdown**:
- The Coco Krispies, Frosted Flakes, and Cheerios contain carbohydrates (sugars and starches) that the yeast can consume. Frosted Flakes and Coco Krispies also have added sugars, which can provide an extra food source.

2. **Activation of Yeast**:
- When you add warm water to the bags with yeast, the warmth wakes up the dormant yeast cells, activating them. Yeast is a type of fungus, and when it becomes active, it begins to feed on the sugars present in the cereals.

3. **Fermentation Process**:
- As the yeast consumes the sugars, it undergoes fermentation. This process produces carbon dioxide gas and alcohol as byproducts. In your scenario, since the bags are sealed tightly, the carbon dioxide gas will build up inside each bag.

4. **Rising and Expansion**:
- The production of carbon dioxide gas will cause the contents of each bag to expand. If the bags are strong enough to contain the increased pressure, you may notice them puffing up as the gas is generated.

5. **Chemical Reaction**:
- The overall reaction of yeast fermenting sugars can be simplified as:
\[
\text{C}_6\text{H}_{12}\text{O}_6 \, (\text{glucose}) \, + \, \text{yeast} \rightarrow 2 \, \text{C}_2\text{H}_5\text{OH} \, (\text{ethanol}) \, + \, 2 \, \text{CO}_2 \, (\text{carbon dioxide})
\]

The end result is a combination of expanded contents due to the carbon dioxide gas and a small amount of alcohol, although it may not be significant due to the short duration of fermentation (15 minutes). After resting, if you were to open the bags, you would likely hear a pop or hiss as the pressure is released.

Overall, the reaction is primarily a biological fermentation process driven by yeast activity.