The pH scale

The pH colour chart. Image credit abcam.com

• Stand for power(potency) or amount of hydrogen in a solution
• It is a measure of acidity or alkalinity
• The pH scale ranges from 0 to 14
• It is used to show how acidic or alkaline a solution is
• Acids have a pH value of less than 7 while
• Bases(alkalies) have a pH value of greater than 7
• A substance with a pH value of 7 is said to be neutral
• An example of a neutral substance is pure/distilled water
• This means it is neither acidic nor alkaline
• Natural water is usually acidic or alkaline depending on the substances that are dissolved in it
• For example carbon dioxide dissolves in water to form carbonic acid
• Limestone dissolves in water to form weak base solutions
• Typical universal indicator is used to measure the pH value of solutions
• It comes as a solution and sometimes in the form of Universal indicator paper
• It also comes with a chart that can be used to interpret the results
• Universal indicator is a mixture of indicators
• The solution being tested is either mixed with Universal indicator solution or
• Universal indicator paper is dipped in the solution
• The ensuing colour change is observed and compared with the accompanying chart to determine the pH of the solution being tested.

To access more topics go to the Combined Science Notes page.