# PhET Simulations

The PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations. PhET sims are based on extensive education research and engage students through an intuitive, game-like environment where students learn through exploration and discovery.

• PhET: Acid-Base Solutions
How do strong and weak acids differ? Use lab tools on your computer to find out! Dip the paper or the probe into solution to measure the pH, or put in the electrodes to measure the conductivity. Then see how concentration and strength affect pH. Can a weak acid solution have the same pH as a strong acid solution?
• PhET: Atomic Interactions
Explore the interactions between various combinations of two atoms. Observe the the total force acting on the atoms or the individual attractive and repulsive forces. Customize the attraction to see how changing the atomic diameter and interaction strength affects the interaction.
• PhET: Balancing Chemical Equations
How do you know if a chemical equation is balanced? What can you change to balance an equation? Play a game to test your ideas!
• PhET: Beer's Law Lab
“The thicker the glass, the darker the brew, the less the light that passes through.” Make colorful concentrated and dilute solutions and explore how much light they absorb and transmit using a virtual spectrophotometer!
• PhET: Blackbody Spectrum
How does the blackbody spectrum of the sun compare to visible light? Learn about the blackbody spectrum of the sun, a light bulb, an oven, and the earth. Adjust the temperature to see the wavelength and intensity of the spectrum change. View the color of the peak of the spectral curve.
• PhET: Build an Atom
Build an atom out of protons, neutrons, and electrons, and see how the element, charge, and mass change. Then play a game to test your ideas!
• PhET: Concentration
Watch your solution change color as you mix chemicals with water. Then check molarity with the concentration meter. What are all the ways you can change the concentration of your solution? Switch solutes to compare different chemicals and find out how concentrated you can go before you hit saturation!
• PhET: Gas Properties
Pump gas molecules to a box and see what happens as you change the volume, add or remove heat, change gravity, and more. Measure the temperature and pressure, and discover how the properties of the gas vary in relation to each other.
• PhET: Isotopes and Atomic Mass
Are all atoms of an element the same? How can you tell one isotope from another? Use the sim to learn about isotopes and how abundance relates to the average atomic mass of an element.
• PhET: Molarity
What determines the concentration of a solution? Learn about the relationships between moles, liters, and molarity by adjusting the amount of solute and solution volume. Change solutes to compare different chemical compounds in water.
• PhET: Molecules and Light
Do you ever wonder how a greenhouse gas affects the climate, or why the ozone layer is important. Use the sim to explore how light interacts with molecules in our atmosphere.
• PhET: Molecule Shapes
Explore molecule shapes by building molecules in 3D! How does molecule shape change with different numbers of bonds and electron pairs? Find out by adding single, double or triple bonds and lone pairs to the central atom. Then, compare the model to real molecules!
• PhET: Molecule Shapes: Basics
Explore molecule shapes by building molecules in 3D! Find out how a molecule's shape changes as you add atoms to a molecule.
• PhET: pH Scale
Test the pH of things like coffee, spit, and soap to determine whether each is acidic, basic, or neutral. Visualize the relative number of hydroxide ions and hydronium ions in solution. Switch between logarithmic and linear scales. Investigate whether changing the volume or diluting with water affects the pH. Or you can design your own liquid!
• PhET: pH Scale: Basics
Test the pH of everyday liquids such as coffee, spit, and soap to determine whether each is acidic, basic, or neutral. Investigate how adding more of a liquid or diluting with water affects pH.
• PhET: Reactants, Products and Leftovers
Create your own sandwich and then see how many sandwiches you can make with different amounts of ingredients. Do the same with chemical reactions. See how many products you can make with different amounts of reactants. Play a game to test your understanding of reactants, products and leftovers. Can you get a perfect score on each level?  Create your own sandwich and then see how many sandwiches you can make with different amounts of ingredients. Do the same with chemical reactions. See how many
• PhET: Reactions & Rates
Explore what makes a reaction happen by colliding atoms and molecules. Design experiments with different reactions, concentrations, and temperatures. When are reactions reversible? What affects the rate of a reaction?
• PhET: Rutherford Scattering
How did Rutherford figure out the structure of the atom without being able to see it? Simulate the famous experiment in which he disproved the Plum Pudding model of the atom by observing alpha particles bouncing off atoms and determining that they must have a small core.
• PhET: Under Pressure
Explore pressure under and above water. See how pressure changes as you change fluids, gravity, container shapes, and volume.