Name: Danielle
Status: student
Grade: 9-12
Location: Australia
Question:
I am doing an experiment involving the
effects of various colas on teeth (I am using pig's
teeth as human teeth were difficult to get). After
being in the cola for 2 days, I weighed them and
was surprised to find that they teeth weighed more
than they did before they were put in. I was not
sure if this was due to the fact that they had
absorbed some of the liquid or because of the black
coating on them or perhaps another
reason I had not thought of?
Replies:
Hi Danielle,
I must say that the gain in weight is a bit strange. What
percentage of weight gain was there? Is it possibly within
experimental error? Possibly there is some water being
absorbed into the spongy interior of the tooth. I suspect
that unless the black deposit is relatively thick, it cannot
materially add to the tooth's weight.
By the way, it is not the Cola (per se) that makes any
difference to the teeth. It is only the amount of phosphoric
acid that the cola contains (and colas strangely do contain
this stuff!). Carbonic acid (caused by the CO2 being
dissolved) will also corrode the tooth, but if the experiment
goes on several days, the CO2 will be long gone (the cola
will be "flat"), so only the phosphoric acid will be left as
a corrosive agent.
NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.
