In the solid state, racemic mixtures may have different physical properties from either of the pure enantiomers because of the differential intermolecular interactions (see Biological Significance section).  The change from a pure enantiomer to a racemate can change its density, melting point, solubility, heat of fusion, refractive index, and its various spectra.  Crystallization of a racemate can result in separate (+) and (−) forms, or a single racemic compound. However, in liquid and gaseous states, racemic mixtures will behave with physical properties that are identical, or near identical, to their pure enantiomers.