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Do you have an experiment that will work to show the effects of carbonated soda beverages on tooth decay?
Question Date: 2004-04-02
Answer 1:

There are two forces at work in tooth decay from soda. The first of these is, as you mentioned, the carbonation. Carbonated beverages contain carbon dioxide, or CO2. Soda like Coca-Cola is made of water (H20), flavored syrup, and CO2. The equation for carbonation is as follows:
H20+CO2--->H2CO3. The right side of the equation is carbonic acid. Tooth decay is caused by acids dissolving the enamel of the teeth.

Now, you might worry that you have been soaking your teeth in acid every time you take a big gulp of soda, and you would be partially correct. Since the carbonic acid that is formed in the soda is dissolved in the water, it comes into contact with your teeth for only a short time every sip.

The second contributor to tooth decay is sugar. Sugar from sodas (and fruit juices, for that matter) coats the teeth every time you take a sip. Bacteria in our mouths break down the sugar into acids, similar to the equation above for carbonic acid. However, since sugar is sticky, it sticks to your teeth and therefore provides a longer time of exposure to acids. That is why sugar is usually the main culprit in tooth decay.

Now, for your experiment. Since you want to study only the effects of carbonation, you must use that as your only variable (ask your science teacher what this means if you are not sure). I would suggest using a drink that contains only carbonation, and no sugar. You also want it to be clear so that you can see what is happening as it happens. Therefore, use 'soda water' or 'seltzer,' which is just CO2 in water. (You could also vary the experiment by having lots of different kinds of soda and checking the effects of *sugar*, but that is a different experiment.)The fizziness you experience when you have a freshly opened can of soda is the carbon dioxide 'escaping.' However, as the soda sits and gets 'flat,' the carbon dioxide is turning into carbonic acid.

If you fill a glass with fresh seltzer, it will dissolve a tooth. However, unless you have lots of baby teeth sitting around the house and your parents are looking for a cool way to get rid of them, I wouldn't suggest using teeth!Instead, take a piece of limestone (which also has calcium in it!), and drop it into the glass. As time wears on, it will dissolve more and more. If you refill the glass with fresh soda, it will dissolve slower than if you just let the same glass sit and turn flat. Why?

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