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.

Approved by eNotes Editorial Team

We’ll help your grades soar

Start your 48-hour free trial and unlock all the summaries, Q&A, and analyses you need to get better grades now.

  • 30,000+ book summaries
  • 20% study tools discount
  • Ad-free content
  • PDF downloads
  • 300,000+ answers
  • 5-star customer support
Start your 48-Hour Free Trial