Optical isomerism 52-53

Question 1

What property must an organic molecule have to have optical isomerism?

Answer 1

Must contain a carbon atom attached to four different atoms or group of atoms.

Question 2

A carbon with four different groups attached is called what?

Answer 2

chiral

Question 3

What is the difference between optical isomers, apart from that they are mirror images, of each other?

Answer 3

Optical isomers rotate plane-polarised light in different directions.

Question 4

How do you draw the two optical isomers that come from the same organic compound?

Answer 4

Draw the compound like a tetrahedral structure with the chiral carbon in the centre and then draw the mirror reflection of the structure.

Question 5

What is a racemic mixture?

Answer 5

A racemic structure is a mixture containing equal amounts of each optical isomer.

Question 6

Describe what effect a racemic mixture has on polarised light and why it has this effect.

Answer 6

A racemic mixture has no effect on plane-polarised light because the rotations cancel each other out, because half of the isomers rotate the light one direction and another rotates the light in the opposite direction.

Question 7

How do the effects to polarised light vary for optical isomers.

Answer 7

One of the optical isomers rotates the light clockwise and the other rotates the light anti-clockwise.

Question 8

Does optical activity matter in plants and animals?

Answer 8

Yes, only one of the optical isomers is synthesised naturally, and only one will interact with an enzyme due to the stereospecific nature of enzymes.