catalyst: a substance that changes the speed of a chemical reaction without affecting the yield or undergoing permanent chemical change*

Question

As you can see NO (nitrogen monoxide) did not undergo a permanent change.

*http://www.chem.purdue.edu/gchelp/gloss/catalyst.html

Lance,

Thank you for your prompt response. I know the definition of catalyst, but I am having trouble figuring out how to find the catalyst in a reaction.

Sarah: If one started with NO, and ended with NO, it was unchanged in the reaction. NO is the catalyst.

Answer 1

Sarah,

To help you further with identifying a catalyst in a chemical reaction, consider the following steps:

1. Look at the reactants (the molecules involved in the beginning of the reaction) and compare them to the products (the molecules resulting from the reaction).
2. If a substance appears in both the reactants and the products without any difference in its chemical structure, it is likely a catalyst.

For example, in this reaction:

A + B + NO -> AB + NO

You can see that NO is part of both the reactants and the products, and it does not undergo any chemical change. So, in this case, NO is the catalyst in the reaction, as it is helping A and B to form AB without itself going through any permanent change.