Question

Suppoose "A" Is any molecule whose mirror image is "B". The " A" Nd "B" Are not superimposed.The mirror image of "B" is "C". The " C" Is superimposed to "A". So what can we say molecule "A" Is chiral r Achiral.????plzzzz help.

Answer 1

I'm not sure I really understand what you're asking, but let's have a go...

Explanation:

Chirality, mirror-images, D/L-configurations and the like are caused by Asymmetrical Carbon Centres. A Carbon atom can make 4 covalent bonds. Their juxtaposition resembles something like the steering wheel of a car:

Let's number the H-atoms:

You can see that H-atoms 2,3 and 4 are numbered Counter-clockwise...

If instead we number them Clockwise, then we get the Mirror-image:

These two are super-imposable, because the bonds are all with (identical) Hydrogen atoms. If we replace `H_2` with another type of atom, or a functional group, then they are still superimposable. Same if another, different one is replacing `H_3`, because you still have two identical groups (H-atoms 1 and 4) that make "flipping" possible: the molecule is still symmetrical.

But the game changes when the central C-atom binds to 4 groups that are ALL different: Suddenly the structure has lost its symmetry, making superimposition impossible!

But make note of the fact that one asymmetrical C-atom can result in only TWO different molecules ( called Enantiomers ).

So, back to your question: B is the mirror image of A, and they are not super-imposable.

If C is the mirror image of B, then it follows that C must be identical to A. You mentioned yourself that A and C ARE Superimposable....

If A and B are not super-imposable, then A (and consequently B) have at least one Chiral Carbon centre...

Achiral means non-chiral.....

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