What is strong acid and weak acid?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

The pH scale is used to measure how acidic or basic a substance is.  The scale goes from 0 to 14.  A substance with a pH of 0 through 6 is considered an acid, while a substance with a pH of 8 through 14 is considered a base.  A pH of 7 is neutral.  Uncontaminated, pure water is neutral.  The closer the number is to 7, the weaker the substance is.  The farther the number is from 7, the stronger the substance is. 

A substance with a pH of 1 or 2 would be a strong acid.  A substance with a pH of 5 or 6 would be a weak acid.

A substance with a pH of 13 or 15 would be a strong base.  A substance with a pH of 8 or 9 would be a weak base.

An example of a strong acid is vinegar.  The pH of vinegar is 2.4.  An example of a weak acid is citric acid.  The pH of citric acid is 4.8.

See eNotes Ad-Free

Start your 48-hour free trial to get access to more than 30,000 additional guides and more than 350,000 Homework Help questions answered by our experts.

Get 48 Hours Free Access
Approved by eNotes Editorial Team