Explore the Acid-Base Lab
Add HCl or NaOH to water and watch a live pH meter and indicator colour. Free, no signup, runs in your browser.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
See it in action
The Acid-Base Lab with sample data entered and the result showing.
What is the Acid-Base Lab?
Add HCl or NaOH to water and watch a live pH meter and indicator colour. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
Neutralisation is used for treating acid spills, antacids, swimming-pool care and wastewater treatment.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Adding a strong acid lowers the pH; adding a strong base raises it.
Mixing equal moles of HCl and NaOH neutralises to pH 7 (water and salt).
Because pH is logarithmic, the last drop near neutral changes it the most.
Add HCl until the pH reaches 2.
Then neutralise with NaOH.
Try the 1 M concentration.
Used for
Pick one to see how it fits.
Chemistry learners
Chemistry students from middle school to university, teachers who need a virtual demonstration, and anyone without access to a lab.
Try it freeTeachers
For teachers: project the Acid-Base Lab (HCl & NaOH) on the board, let students predict the result, then run it together and test this: Then neutralise with NaOH. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
What happens when HCl reacts with NaOH?
They neutralise each other: HCl + NaOH → NaCl + H₂O. If the moles are equal the solution ends up at pH 7.
Why does pH change so fast near neutral?
With few ions of either kind left, one extra drop makes a big relative change, and pH is a logarithmic scale.
Is the Acid-Base Lab (HCl & NaOH) free to use?
Yes. The Acid-Base Lab (HCl & NaOH) is free, needs no signup or download and runs in your web browser. It is part of the Chemistry group of AZRS simulations.
Does the Acid-Base Lab (HCl & NaOH) work on a phone or tablet?
Yes. The Acid-Base Lab (HCl & NaOH) takes touch input as well as mouse input, so you can use its 1 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Acid-Base Lab?
1. In the Acid-Base Lab (HCl & NaOH), use the controls to change Concentration of HCl and NaOH. The simulation reacts instantly. 2. In the Acid-Base Lab (HCl & NaOH), pick an option such as 0.01 M, 0.1 M, 1 M to switch modes or load an example. 3. In the Acid-Base Lab (HCl & NaOH), press "+ HCl drop", "+ NaOH drop", "+ 2 mL HCl", "+ 2 mL NaOH" to start, reset or change what is happening. 4. Start with this experiment: Add HCl until the pH reaches 2. Drag any glowing handle, object or slider with your mouse or finger and the Acid-Base Lab (HCl & NaOH) responds in real time. 5. Change one setting at a time and watch which readout moves, then compare it with this idea: Adding a strong acid lowers the pH; adding a strong base raises it.
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Try the Acid-Base Lab now
Add HCl or NaOH to water and watch a live pH meter and indicator colour. Free to use.
Try it free