How to find out whether a given molecule is chiral or achiral? By the definition one has to construct a molecular model and its mirror image (this is always possible), e.g. using a commercial molecular model building set, and then to try to bring these into superposition.

If there is success, then the two models are identical and therefore achiral.

If we do not succeed, then there are two possibilities:

• Either the two models are really nonsuperposable. In that case they are chiral.
• Or they can be superpopsed by a really clever manipulation (in which case they are achiral), but we are not clever enough to find this manipulation.

Unfortunately, that latter case can never be excluded, in particular not with larger and conformationally mobile molecules.