|MadSci Network: Chemistry|
There really isn't a relationship between carbonation and caffeine in carbonated soft drinks (csd's). Carbonation is added for mouth feel and is adjusted based on the type of drinkability that the product developer (the person responsible for taking a csd concept to market) is looking for. If you are looking for "chuggability" (chugging is drinking a csd really fast, like when you are very thirsty) then you will add less carbonation. Try an experiment and see which is more "chuggable" Seltzer Water or Mountain Dew. Hint: Mountain Dew is less carbonated!! Warning!!! Get ready for some serious BURPING!!!
If you are looking for specific relationships between carbonation and another ingredient in a csd, then I really can't help you. However, I can tell you that carbonation is directly related to pressure and temperature. Pressure and temperature effect the solubility of CO2 in the csd. If you release the pressure in a soda bottle, then the soda will start to lose CO2 and go flat. A cold csd will retain more CO2 than a warm csd will.
Caffeine provides a characteristic flavor to csd's. It's concentration is variable from csd to csd and dependent upon the flavor profile (how the product developer wants the csd to taste.) You can find much more information about caffeine on the Pepsi website ( http://pepsi.com ) under the Help/FAQS section.
I hope that this response to your question helps to point you in the right direction for your school project.
Your "Chuggable and Burpable" Mad Scientist Dave
Try the links in the MadSci Library for more information on Chemistry.