What does pH mean?

This is a measure of how acidic or alkaline a substance is. The initials pH stand for "Potential of Hydrogen." Acids have pH values under 7, and alkalis have pH values over 7. If a substance has a pH value of 7, it is neutral-neither acidic or alkaline.

Because the pH scale is logarithmic, a difference of one pH unit represents a tenfold, or ten times change. For example, the acidity of a sample with a pH of 5 is ten times greater than that of a sample with a pH of 6. A difference of 2 units, from 6 to 4, would mean that the acidity is one hundred times greater, and so on.

How is the pH of a substance measured?

A pH can be measured by dipping a pH paper into solutions such as water or other substances.

What is pH paper?

Also known as litmus paper, this is a special type of paper containing a chemical that will tell you the pH of a substance by the colour it turns when it is dipped into the substance.

Where I can get pH paper?

You can usually find pH paper at any beer or wine making shop. Other possibilities include your local pharmacy or hair salon. You could also ask your science teacher. Be sure to use the wide range pH paper showing pH of 1 to 12.

What is the pH of normal rain?

Normal rain has a pH of about 5.6. It is slightly acidic because naturally present carbon dioxide from the Earth's atmosphere dissolves in the rain drops to form carbonic acid.

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