Question: I am studying different types of food, what investigations can I do with cookie dough?
Answer: This question reminds me of Rob Cockerham’s “How Much is Inside?” investigations. There are various silly things you could calculate with cookie dough, but why not stick to science.
Introduction | Method One | Method Two | Results
We bought two different brands of sugar and chocolate chip cookie, so all told we had four different cookie types to test. The consensus was simply to look for one ingredient in the cookies and compare the amounts present in each cookie. Our first idea was to see what made the cookie rise.
Method One: Potassium Carbonate
For the first experiment I wanted to see how cookies rise, and also
compare the differences in these mechanisms between 
different cookie
types and brands. Every cookie would have a compound similar to potassium
carbonate which breaks down under the heat of the oven to create CO2
gas that pushes the cookie out and makes it rise. I decided to use
HCl to make the cookie’s rising component break down into CO2;
however, there was so little that it was impossible to measure accurately.
Instead I decided to measure and compare a more abundant component,
salt.
To find the amount of salt in the cookie dough I decided to dissolve bits of cookie dough in water. Then when the salt was dissolved, I did a silver nitrate test to find the salt content. The first step of the lab was to be able to isolate a relatively clear solution containing the cookie dough’s salt content. The solution needed to be clear in order for the white silver chloride precipitate to be visible. After (unsuccessfully) trying to filter the mixture of cookie dough and water, we used a centrifuge to separate the unneeded cookie dough from the water. First the dough was mixed with the water so that there were no large chunks left, and then the test tube was put in the centrifuge. The liquid was extracted from the test tube after it was run in the centrifuge and the process was repeated until the liquid was sufficiently see-through (that is to say, there would be enough of a contrast between the color of the liquid and the silver chloride to make it differentiable):
Once the optimum opacity was achieved AgNO3 was added and the silver chloride’s mass was measured. From that information the mass of the salt could be extrapolated:
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