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How to Make a Simple PH Probe With Chemicals

The pH of any substance is really just a count of the number of hydronium ions (ionized hydrogen atoms) it contains as compared to water. The lower the pH the more hydronium ions are present and the more acidic it is. In general there are three types of acids: weak, strong, and polyprotic. Only the first two are of interest for this particular chemical pH probe, which is with simple items.

Things You'll Need

Flowers, such as crape-myrtle
Acetone
Mortar and Pestle
Filter paper or Coffee filters
Funnel
Several small vials
Eye dropper
Samples of substances to test for acidity

Instructions

- 1
  
  A mortar and pestle will grind plants to help extract various chemicals.
  
  Grind several flowers and 10 milliliters of acetone with a mortal and pestle.
- 2
  Place the filter paper or coffee filter in the funnel and pour the liquid from the mortar through the paper into a small vial. This clear liquid contains several pH-sensitive pigments or dyes and will act as an indicator of the presence of acids.
- 3
  Use the eye dropper to place several drops of the indicator into another vial and add some of the first substance to test. It will turn pink if it is an acid and clear again if it is a base.

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