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?

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!

ÒThe thicker the glass, the darker the brew, the less the light that passes through.Ó Make colorful concentrated and dilute solutions and explore how much light they absorb and transmit using a virtual spectrophotometer!

Starting from atoms, see how many molecules you can build. Collect your molecules and view them in 3D!

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!

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.

In this activity, students observe fluid motion and the formation of convection cells as a solution of soap and water is heated. This procedure can be performed as a demonstration by the teacher, or older students can conduct the experiment themselves. A list of materials, instructions, and a description of the convective process are included.

Watch the rubber bands vibrate on homemade guitars in this video segment adapted from ZOOM as cast members talk about pitch and demonstrate how to make a cereal box instrument.

This video segment, adapted from ZOOM, explores the different sounds that a simple drinking straw can produce when you cut the straw and blow into it.

This video segment, adapted from ZOOM, demonstrates how to use a drinking straw and a bottle full of water to make low- and high-pitched sounds.

This video segment adapted from A Science Odyssey uses animation and archival footage to provide an overview of the theory of plate tectonics.

This video segment adapted from NOVA uses animation to show the relationship between the movement of a tectonic plate and whether volcanoes on the Hawaiian Islands are active or dormant.

In this open-ended activity (magic trick), students look at attraction between molecules as they pour water along a strong from one cup to another cup. Students develop an explanation for how the process works.

In this interactive periodic table from the NOVA Web site, find out the role of various elements in making fireworks.

A simple lab emphasizing experimental design and controls to draw conclusions about what factors speed up and which slow down the rate at which sugar dissolves in water.

Science Phenomena: HS Physical Science - Chemical Reactions - This video shows a chemical reaction of sodium bicarbonate (baking soda), calcium chloride (road salt), and an indicator phenol red. The chemicals react to form calcium carbonate, sodium chloride, and carbon dioxide gas. This changes the pH inside the bag resulting in a color change in the phenol red. As much air as possible should be removed from the bag as possible to show the production of the gas. This could be used as an example of chemical reaction that releases energy (exothermic). Since the bag is sealed it could be massed before and after to show the conservation of mass (atoms). This phenomenon was submitted by Brian Babulic.

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?

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?

This phenomenon uses a supersaturated solution of sodium acetate. Clicking the metal disc releases a small number of crystals of sodium acetate which act as nucleation sites for the crystallization of the sodium acetate into a hydrated salt. Energy is released from the crystal lattice. The heating pack can be placed in boiling water and the sodium acetate can be dissolved again. This phenomenon shows how bond energy can be released. It also shows the importance of chemical engineering and could lead to a section where students design a device (or application) of their own.

Watch a reaction proceed over time. How does total energy affect a reaction rate? Vary temperature, barrier height, and potential energies. Record concentrations and time in order to extract rate coefficients. Do temperature dependent studies to extract Arrhenius parameters. This simulation is best used with teacher guidance because it presents an analogy of chemical reactions.