soda bottle material and carbonic acid research hypothesis

[pinkpiggy9]

My science fair project is:
Does the material of the storage container(e.g. glass bottle, PET bottle, Aluminum bottle) affect the release of carbonic acid from Regular Coca Cola over time?
I am currently doing research to develop my hypothesis. I am not exactly sure what sort of thing I need to research to be able to support the prediction part of my hypothesis. I could use any help you can offer; sources, advice, anything.
Thank so much.

[deleted-71709]

Hello pinkpiggy9,

I think what you are really interested in is how does the material of a storage container affect the release of carbon dioxide gas from Coca Cola, not carbonic acid.

What you are interested in is the "permeability" of the materials of the containers. Permeability is the property of a material that controls how gasses and liquids to pass through it. The amount of gas or liquid that passes through a material is primarily affected by the permeability of the material, the nature of the gas or liquid, and the pressure difference on each side of the material.

As an example, have you ever noticed how quickly a helium filled balloon looses it's gas, compared to a balloon filled with air? That is because the size of helium atoms is so small, compared to air atoms (oxygen and nitrogen) that the helium seeps through the microscopic pores in the rubber, but the air atoms are too big to pass through those pores. These pores determine the permeability of the material, and the nature of the gas, that is the size of the atoms, determines how fast the gas passes through the material.

I suggest you look into the permeability of the materials you mentioned in your note. I suspect you will find they are really quite similar, and should expect them to perform very much the same. My experience with preserving carbonated beverages tells me the type of seal on the container is far more important than the material from which the container is made. You might think about that.

Good luck in your investigation, and have fun!

[deleted-71588]

Testing any hypothesis with respect to any differences in the container material would require very expensive equipment and/or a very long elapsed time (think years).
Proving that some slight difference in the seal in your samples isn't effecting your results will also be difficult.

I would put this into the very interesting subject but not a viable Science Fair project because of the difficulties/expense in testing and measurement.

[pinkpiggy9]

I am running this experiment twice in a way. The first time I will just take of the cap, but in the second experiment I am going to break the seal and re-put on the cap. Edneu3 thank you for your advice about permeability, and carbon dioxide. i was originally going to test seals, but my teacher thought that didn't seem like as strong of an experiment so she encouraged me to combine the two some way and the above is what we came up with. We still have to alter the question a little bit to match the experiment, but we are still working on that.

[deleted-71709]

It sounds like you are being successful in refining your ideas.

As you proceed to evaluate seals keep a couple things in mind.

The rate at which carbon dioxide will be released from the beverage will be controlled to a large degree by the temperature of the liquid. This is because the "solubility" of carbon dioxide, or any gas for that matter, in a liquid is controlled by temperature and pressure. You should do some research on solubility of gasses to support your experiment.

Secondly, as you plan to "re-put on the cap", this will introduce a large amount of variability into your experiment. I'm sure you will find it very difficult to reseal containers all the same way every time you try. A good way to experimentally account for this is to run MANY samples, at least 20 of each container/seal type, and use statistical analysis to study your results. Here's another area of research for you - the use of statistics in experiments.

Have fun!