Beer's Law Lab: Absorbance & Concentration
Shine light through a colored solution and see how absorbance depends on concentration, width and wavelength.
Shine light through a colored solution and measure how much is absorbed. Drag the concentration and the width of the cuvette, or drag the wavelength marker on the spectrum. Absorbance = ε × width × concentration.
About the Beer's Law Lab: Absorbance & Concentration
Free beer's law lab: absorbance & concentration. Shine light through a colored solution and see how absorbance depends on concentration, width and wavelength. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for chemistry labs, the beer's law lab: absorbance & concentration runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Shine light through a colored solution and see how absorbance depends on concentration, width and wavelength. Use it to explore chemistry labs ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Beer's Law Lab: Absorbance & Concentration
- Use the controls to change Solute, Concentration, Cuvette width, Wavelength of light. The simulation reacts instantly.
- Pick an option such as Potassium permanganate, Copper sulfate, Cobalt chloride, Nickel nitrate to switch modes or load an example.
- Press "Use the best wavelength" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Find the wavelength with the highest absorbance for each solute.
- Double the concentration and check the absorbance doubles.
- Make the cuvette three times wider and compare.
- Read off the concentration that gives 50 percent transmittance.
Key ideas you can learn
- Absorbance A = ε × width × concentration.
- Doubling the concentration or the width doubles the absorbance.
- Transmittance T = 10 to the power of minus A, so the light dims exponentially.
- A solution absorbs the wavelengths that are the opposite color to what you see.
Where this is used in the real world
Hospitals measure hemoglobin and glucose, water labs test pollutants, and chemists find unknown concentrations with spectrophotometers using this law.
Who is this simulation for?
Students preparing for practical exams and teachers who want a virtual lab. You can repeat the experiment without chemicals, waste or safety risks.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
What is absorbance?
A measure of how much light a sample absorbs. Each unit of absorbance cuts the light by a factor of ten.
Why do labs choose the peak wavelength?
At the wavelength where the solute absorbs most, small changes in concentration give the biggest change in the reading.
Is the Beer's Law Lab: Absorbance & Concentration free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Beer's Law Lab: Absorbance & Concentration work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.