Created in collaboration between Arizona State University and Carnegie Mellon University, REAL CHEM is designed to help educators engage, inspire, and build confidence in their general chemistry students.

Backed by years of teaching experience and learning science research, we are committed to the idea that reaching students with varying levels of academic preparation is the key to boosting their success. That’s why we developed cinematic videos that break down complex concepts, problem-solving assignments using real-world data, and active learning strategies to form the foundation of our courseware.

With over 11,000 students using REAL CHEM across 30 institutions, we’re making an impact on retention and student outcomes. When students see themselves in chemistry, they explore deeper, solve harder problems, and push their understanding further.

Let’s build bonds that last beyond the classroom.

— The REAL CHEM Team

Chemical Kinetics of the Ozone Hole

A layer of ozone in the stratosphere blocks most of the Sun’s ultraviolet radiation from reaching the Earth’s surface. Too much ultraviolet radiation can lead to skin cancer and interferes with photosynthesis in plants, making the ozone layer vital to life on Earth. Starting in the late 1970s, the ozone layer was attacked by a class of chemical compounds called chlorofluorocarbons or CFCs. CFCs are inert at Earth’s surface, but when they reach the stratosphere, CFCs are exposed to more intense ultraviolet radiation that breaks down the molecules to form chlorine radicals that rapidly destroy ozone, leading to the formation of the ozone hole.

I love using the chemistry of the ozone hole to investigate chemical kinetics in my General Chemistry II class. Upon first glance, the chemical reaction for the destruction of ozone is simple: one ozone molecule and one oxygen atom collide and form two molecules of diatomic oxygen. The relatively slow rate of this reaction does not explain the sharp drop in stratospheric ozone concentrations that are observed when the ozone hole is formed each year at the South Pole. The chemistry of this process starts to get interesting with the addition of chlorine, which acts as a catalyst. The process gets even more interesting when you consider the importance of the seasonal variation of solar radiation, the weather conditions, the presence of additional catalysts, and other variables that affect the destruction of stratospheric ozone at the Poles.

To connect kinetics and the ozone hole in General Chemistry II, we work through the REAL CHEM “Catalyst in the Clouds” Exploration activity to use a straightforward reaction chamber simulation to make experimental measurements of the reaction rate. We then interpret the collected data to determine reaction orders, the rate law, and rate constant and see the significant increase in reaction rate when the chlorine catalyst is added. This activity allows students to connect the concepts of chemical kinetics to the chemistry involved in forming the ozone hole.

To reinforce the importance of chemical kinetics, we discuss the lasting global implications of the Montreal Protocol, one of the greatest examples of scientific discovery informing effective international policy to solve a global environmental issue. Scientists and policy makers came together in 1987 to eliminate the use of CFCs that contribute to the catalytic destruction of ozone in the stratosphere. The ozone hole still forms each year, but it is shrinking over time, providing an annual visual reminder of the environmental challenges we can solve as a global community when we understand the chemistry and use that to inform policy

(Image from REAL CHEM Exploration “Catalyst in the Clouds”)