One skill students of organic chemistry need to develop is the ability to manipulate three dimensional objects. To compare the mirror image of 2-propanol to the original, you can rotate one object by 180 o to align two groups then superimpose the structure with the original object. They are superimposable and represent the same molecule. There is only one structure for 2-propanol. We have seen that a molecule with a carbon atom bonded to four different groups is chiral.
Lets consider a specific example, lactic acid.
C-2 of lactic acid has 4 different groups as is called a chiral carbon atom. There are two mirror image isomers of lactic acid. These isomers have the same bonding arrangement but are nonsuperimposable. These isomers are mirror images of each other and are called enantiomers. To compare the mirror image of lactic acid to the original, you can rotate one object by 180 o to align two groups then superimpose the structure with the original object.