1
$\begingroup$

How do we know if this following molecule is Super Imposable mirror image or Non Super Imposable mirror image ? [See Image attached]

Molecule

$\endgroup$
  • 1
    $\begingroup$ How do you know your left and right hands are not superimposable? (Or maybe they are?) $\endgroup$ – Ivan Neretin Apr 30 '19 at 10:38
  • $\begingroup$ Yes they are super imposable ? Because if we keep the mirror image of right hand on right hand , it's the same . $\endgroup$ – Nityoday Tekchandani Apr 30 '19 at 11:00
  • $\begingroup$ Super impossable mirror images means 2 mutualy mirror images, where you can identify one such an image with the other by its translation and rotation. Involve your imagination. $\endgroup$ – Poutnik Apr 30 '19 at 11:13
  • $\begingroup$ @Nityoday Tekchandani No, left and right hands are not super impossbale. You cannot formally by a geometry way identify the left(right) hand and its mirror image right(left), implying there is a mirror symmetry. $\endgroup$ – Poutnik Apr 30 '19 at 11:17
  • $\begingroup$ Okay, so according to what I understood, that a real object and it's mirror image, if they look same , they are super imposable , else non super imposable ? Also, then the question's answer would be Super Imposable ? $\endgroup$ – Nityoday Tekchandani Apr 30 '19 at 11:30
2
$\begingroup$
  • Take 2 round, soft objects like potatoes or apples.
  • Pin into each 4 pins of 3 different kinds ( 1 + 2 + 1 ),
    pointing to the most different directions.
  • Call the 1st pin bromine, the 2nd one hydrogen, the 3rd one ethyl.
  • Do the same for the other potato to be the mirror image of the first one.
  • Try to rotate one of them to look like the other.
  • If you succeed, they are superimposable.
  • Now, replace one of the same pins on both objects by another - 4th kind - of pins in such a way that they are still mutual mirror images.
  • Try to match them the same way you tried previously.
  • If you succeed, they are superimposable.

The summary:

  • While there are 2 hydrogen atoms on a carbon atoms - or more generally, there are only 3 kinds of groups on a C atom - the groups/atoms of the same kind are interchangeble and you can rotate the molecule to match the mirror image.
  • If there are 4 different groups on C atoms, you cannot make such a match.
  • Said by other way, the former case has a plane of symmetry, the latter case does not.
| improve this answer | |
$\endgroup$
  • $\begingroup$ Can we rotate the mirror image in x,y,z all the directions ? $\endgroup$ – Nityoday Tekchandani Apr 30 '19 at 11:33
  • $\begingroup$ Do you have in mind any reason why we cannot ? Imagine 2 pieces of LEGO. How would you determine they are identical ? You rotate them all the ways until you see they are the same - or not. $\endgroup$ – Poutnik Apr 30 '19 at 11:38
  • $\begingroup$ Okay, I tried this , $\endgroup$ – Nityoday Tekchandani Apr 30 '19 at 12:03
  • $\begingroup$ Step one : m.imgur.com/gallery/1cLeqQd Step two : m.imgur.com/gallery/Zyy2xfx I can successfully rotate the mirror image to get it like the first one !! Hence I've come to a conclusion that these are super Imposable. Am I correct ? $\endgroup$ – Nityoday Tekchandani Apr 30 '19 at 12:05
  • $\begingroup$ for some reasons I cannot get the images. but if you talk about the fiirst 1+2+1 case, you are correct. $\endgroup$ – Poutnik Apr 30 '19 at 12:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.