The pH scale

The pH scale is a measure of how acidic or basic (alkaline) a substance is. It ranges from 0 to 14, with 7 being neutral (neither acidic nor alkaline), like pure water. Acidic substances have a pH value below 7. The lower the number, the more acidic the substance is. For example, orange juice and vinegar are acidic. Basic (alkaline) substances have a pH value above 7, like many cleaning agents. As a general rule, the higher the number, the more alkaline a substance is. The pH scale helps scientists and ordinary people understand the properties of different liquids and solutions, from food and drink to body fluids.

You can use the widget below to determine the pH values of various substances. Just give it a try!

Once you have tested all the compounds, sort the following examples according to their acidity:

Drain cleaner

Blood

Milk

Orange juice

Soap

Where would water be in this list? Enter the hypothetical position if we assume that 6 places are available.