How might you tell whether or not your toothpaste contained calcium carbonate, #CaCO_3#, or perhaps baking soda, #NaHCO_3#, without looking at the ingredients label?

1 Answer
Dec 31, 2016

Answer:

To tell whether the toothpaste contains any carbonate or bicarbonate, drop a small amount into an acid such as vinegar. Look for bubbles of carbon dioxide.

Explanation:

Here are the chemical equations:

Carbonate:

#"CO"_3^{2-}+2 "H"^+"(aq)"\rarr"H"_2"O"+"CO"_2"(g)"#

Bicarbonate:

#"HCO"_3^{-}+"H"^+"(aq)"\rarr "H"_2"O"+"CO"_2"(g)"#

There are other household acids such as most toilet bowl cleaners, but vinegar is safest. Be sure to rinse your container well and wash your hands after the experiment.