« Return to AACT homepage

AACT Member-Only Content

You have to be an AACT member to access this content, but good news: anyone can join!

Need Help?

Acid & Base Guys Video Questions Mark as Favorite (4 Favorites)

ACTIVITY in History, Acid & Base Theories, Strong vs Weak. Last updated June 13, 2018.


In this activity, students will watch a video about the history of acids and bases. They will learn about the evolution of these theories, from Lavoisier to Arrhenius, Bronsted-Lowry, and Lewis.

Grade Level

High and Middle School


By the end of this activity, students should be able to

  • Describe how the various acid and base theories have progressed through the centuries.
  • Understand the pH scale.

Chemistry Topics

This activity supports students’ understanding of

  • Acid & Bases
  • Acid/Base Theories
  • Strong vs. Weak Acids
  • pH
  • History of Chemistry


Teacher Preparation: minimal

Lesson: 10 minutes



  • No specific safety precautions need to be observed for this activity.

Teacher Notes

  • The Acid & Base Guys video was developed as a part of the AACT original video series, Founders of Chemistry. The entire series can be found here.
  • The running time of this video is six minutes.
  • This video is intended for students to watch, and for teachers to integrate into their curriculum.
  • The student questions/answers are presented in sequential order in the video.
  • An answer key has also been provided for teacher reference.
  • Videos can be shown with the use of a classroom projector, or teachers can generate a Student Video Pass through their AACT membership to allow students to independently access the video.

For the Student



While watching the Founders of Chemistry Video about The Acid & Base Guys, answer the following questions:

  • What was the first definition of acid and who thought of it?
  • Why was that first definition wrong?
  • What was Arrhenius’s definition? What observation made him think of this definition?
  • What does the pH scale measure?
  • When was the pH scale created?
  • What is a Bronsted-Lowry acid? What is a Bronsted-Lowry base?
  • What is a Lewis acid? What is a Lewis base?
  • Which definitions do chemists use today? How do today’s chemists decide which definition to use?