Chemistry · Lesson Worlds
Acids: interactive science lab
Change pH and prove that acids turn the indicator one way and bases the other.
Free · No account required · Runs in your browser
What will you learn?
pH below 7 is acid. pH above 7 is base. 7 is neutral. The indicator color is the readout.
How does the lab work?
Observe the simulation, make a prediction, change a variable, run the experiment, and explain the result. Finish with a challenge that tests your understanding.
You can change: pH. Compare what happens and connect the result to the scientific explanation.
Try a comparison in Acids
Start with the lab’s initial settings. Choose one control below, predict the result, and change that control while keeping the others fixed. Record the setting and what you observe before making a second change.
- pH: the lab starts at 7; its available range is 1–13.
For a named starting condition, try Acid, Water, Base. A preset can change several settings: check the controls before treating two presets as a one-variable comparison.
Questions to discuss during the activity
- Watch what happens. The color is quiet. That is water. Watch the flask sit near pH 7.
- Name the cause. Low pH means many H+ ions — acid. High pH means few H+ — base. An indicator changes color so you can see that count. pH counts how acidic a mix is.
- Change something. Lower pH and the flask should go acid-colored. Change pH, then mix.
- Guess before you run. If we set pH to 2, the flask will… Guess what will happen, then run to check.
After your comparison, explain how the observations connect to this idea: pH below 7 is acid. pH above 7 is base. 7 is neutral. The indicator color is the readout. Name one condition you held fixed and one feature of the real world this model simplifies. A completed run is a starting point for discussion, rather than proof of mastery.
Who is it for?
Curious learners exploring chemistry. A parent or teacher can help younger learners read the instructions and discuss the results. Choose by topic and prior knowledge rather than a fixed grade level.
Is this lab free?
Yes. This interactive lab is free without signing in or a paid membership.
No app download is needed; interactive play requires JavaScript and a modern browser.
Use this activity with a learner
Families and educators · choose by prior knowledge
Learning goal: pH below 7 is acid. pH above 7 is base. 7 is neutral. The indicator color is the readout.
Before you begin: Read the controls for pH. Make one prediction before changing a setting.
Check understanding: Ask for one observation, the evidence that supports it, and a question to investigate next.
A simulation simplifies the real world. Explain which conditions stayed fixed; a successful run alone does not demonstrate mastery.
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