Virtual Lab - Basics of the pH Scale



Learning Intentions

  • To understand how the pH scale is logarithmic, not linear
  • To practice graphing data in Excel
  • To learn the pH of some common substances


Notes

Open the PhET simulation pH Scale: Basics.

Drag the green target over the bottom of the container, so that you can read the pH of the contents.

Pull the blue knob on the top pipe to add water to the container.

Push the red button on the eye dropper to add a liquid to the container.

You can drain the container by pushing the reset button in the bottom-right corner, or by pulling the blue knob on the bottom-left of the container.


Questions

You will need to use the Internet to find the answers to some of these questions.

  1. List the 12 substances tested, from most acidic to most basic.
  2. Compare the acidity of battery acid and vomit.
    1. Which is stronger (has a lower pH)?
    2. How many times stronger is it?
    3. Why is vomit so strongly acidic?
  3. Add 0.10 L of battery acid to the container, then add 0.10 L of water at a time to complete the following chart.

    Level of
    Dilution
    		 Volume of
    Battery Acid
    		 Volume of
    Water
    		 Total
    Volume
    		 pH
    None (1:0)
    		 0.10 L
    		 0.00 L 0.10 L
    		 1.00
    1:1 0.10 L 0.10 L
    1:2

    ...

    1:9


  4. In Excel, create a graph with the pH of the battery acid solution on the vertical axis and the dilution factor (0 to 9) on the horizontal axis. You do not need to include any of the volumes (acid, water, or total).
  5. When diluting an acid, safety dictates that you should add the acid to the water, rather than adding the water to the acid. Why is this?
  6. Add 0.10 L of drain cleaner to the container, then add 0.10 L of water at a time to complete the following chart.

    Level of
    Dilution
    		 Volume of
    Drain Cleaner
    		 Volume of
    Water
    		 Total
    Volume
    		 pH
    None (1:0)
    		 0.10 L
    		 0.00 L 0.10 L
    		 13.00
    1:1 0.10 L 0.10 L
    1:2

    ...

    1:9


  7. In Excel, create a graph with the pH of the drain cleaner solution on the vertical axis and the dilution factor (0 to 9) on the horizontal axis. You do not need to include any of the volumes (drain cleaner, water, or total).


Assessment

Beginning: Missing a lot of questions, and/or lots of wrong answers.

Developing: Missing some of the questions, and/or quite a few wrong answers, and/or poorly created graphs.

Applying: Includes all questions, most answered correctly, with mostly properly formatted graphs.

Extending: Includes all questions, answered correctly, with perfectly formatted graphs.