Glass can be formed naturally; for example in volcanoes or when lightning strikes a sandy beach and it has been produced by humans for thousands of years. Glasses can take on many different appearances, colors, and properties. Thus, it may be surprising that our understanding of the exact structure of glass is not complete, even after such a long time. Very often, you will hear glasses described as amorphous. This word is derived from Greek and means without shape. So we have a rough idea that glass is somehow shapeless. In the following we will see, how we can investigate the atomic arrangement in glass using modern techniques.

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To compare and predict the performance of heterogeneous catalysts, it is important to have a standard way to describe the catalytic activity. The  catalytic activity describes how good a catalyst is working for a given reaction. When we have a normalized measure for the catalytic activity, we can compare different catalysts and find out which is the best one. But this means, that we have to do a lot of experiments and try and fail until we found a good catalyst. It would be better, if we could predict whether a material will be a good catalysts for a given reaction or not.

The catalytic activity is dependent on the physical and chemical properties of the catalyst material, and of course the reaction conditions, i.e. temperature, pressure and the reactant concentrations. So, if we want to predict the catalytic activity of a material, we have to have information about the material's properties. As we will see in the following, a few parameters can be sufficient to get an idea on the performance of a material as a catalyst for a given reaction. To predict the catalyst quality we can use the Sabatier principle.

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