How might you tell whether or not your toothpaste contained calcium carbonate, CaCO3, or perhaps baking soda, NaHCO3, without looking at the ingredients label?

1 Answer
Oscar L.
Dec 31, 2016

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:

CO2−3+2H+(aq)→H2O+CO2(g)

Bicarbonate:

HCO−3+H+(aq)→H2O+CO2(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.

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