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ZingPath: pH, Acids, and Bases

Acid-Base Indicators

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pH, Acids, and Bases

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Lesson Focus

Acid-Base Indicators


Learning Made Easy

You get to explore the concept of pH as you learn about dissociation of acids and bases. Perform a virtual titration to bring neutralization and end points to life.

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Now You Know

After completing this tutorial, you will be able to complete the following:

  • Realize that acidity of the environment can cause some compounds to change color.
  • Explain the practical applications of acid-base indicators.
  • Explain that each acid-base indicator has specific end points.

Everything You'll Have Covered

What are indicators?

~ Indicators are chemical dyes that change color depending on the pH of a solution. They are weak acids or bases that change color when they reach a specific pH. An example of an indicator is litmus paper, which changes color depending on the acidity or alkalinity of a solution.

What is the end point of an indicator?

~ The end point is the pH level at which an indicator changes color. Each indicator determines only one pH value.

What purpose do indicators serve in the laboratory?

~ Scientists use indicators in the laboratory to test the pH levels of solutions. By using different indicators that change colors at different pH levels, scientists can narrow down the pH level of a solution.

List the pH values that can be determined using three common indicators: litmus paper, methyl orange, and phenolphthalein.

~ Litmus paper will change color in solutions with pH values ranging from 4.5 to 8.3. Methyl orange will change color in solutions with pH values ranging from 3.1 to 4.4. Phenolphthalein will change color in solutions with pH values ranging from 8.3 to 10.

Tutorial Details

Approximate Time 2 Minutes
Pre-requisite Concepts Students should be familiar with acid, base, and chemical dye.
Course Chemistry
Type of Tutorial Animation
Key Vocabulary acid, base, chemical dye