 When we say green chemistry we mean environmentally friendly chemical processes and doing chemistry with personal safety and the environment in mind. There are 12 principles designed to help make chemistry greener. We will discuss each of these 12 principles with an example. Let's start with a simple concept. If you keep your room neat and tidy you won't have to clean up as much. If your room gets really messy then you will have a lot to clean up. The same concept is applied in green chemistry. If we prevent waste from being produced then there would be less to clean up. Now this is almost impossible to have zero waste for any given chemical reaction. On a global scale the beauty of this principle is that it can be applied to almost every single chemical reaction conducted. For example polystyrene is a fossil fuel derived polymer used to make all disposable cups and packaging materials. The polymer itself needs to be expanded before it can be used in packaging. Traditionally this was done with CFCs or chlorofluorocarbons which deplete the ozone layer. Now this is done with carbon dioxide waste from other industrial processes. Instead of releasing carbon dioxide into the atmosphere and contributing to the greenhouse effect this is contained and used to expand polystyrene. So there is no additional carbon dioxide being released into the atmosphere.