Universal indicator is a mixture of a variety of other indicators and can be used to measure the approximate pH of a solution. A more accurate value can be obtained using a pH probe.

A student exhales through a straw into a solution of tap water and aquarium pH indicator. The changing colour demonstrates that increasing the amount of dissolved carbon dioxide causes water to ...

Once we have the indicator solution ready we canbegin the experiment. Make sure you have the pH scale eitherprinted out or on a computer (if using a computer, keep it far away from the liquids).