3.7

Question 1

What was a carbon atom have for the molecule to display optical isomerism about that carbon atom?

Answer 1

4 different substituents attached to one carbon atom

Question 2

What are the similarities and differences between two optical isomers?

Answer 2

Same: -Same atoms and bonds, but they are not super-imposable mirror images of one another. -Not identical in chemical properties. Difference: -Differ in the way they rotate plane polarised light- rotate the plane of polarisation y the same angle but in different directions

Question 3

What word is used to describe optically active molecules?

Answer 3

Chiral

Question 4

What is the pair of isomers called?

Answer 4

Enantiomers

Question 5

What is the chiral center?

Answer 5

The four carbon different constituents attached to it.

Question 6

How is the chiral center denoted?

Answer 6

C*

Question 7

Give examples of chiral molecules. (Draw one of them both enantiomers)

Answer 7

• All alpha amino acids except glycine
• 2-hydroxypropanoic acid

Question 8

How is light polarised?

Answer 8

By passing it through a polaroid filter, so oscillations are only in one plane.

Question 9

What effect does the racemic mixture have on a plane polarised light?

Answer 9

none, as the rotation by each enantiomer cancels out to nothing

Question 10

What effect does the + have on a plane polarised light?

Answer 10

Rotates plane polarisation by x^0 clockwise

Question 11

What effect does the - isomer have on the plane polarised light?

Answer 11

Rotates the plane polarisation by x^0 anti-clockwise

(the same angle, opposite direction)

Question 12

What is a structure of a polarimeter?

Answer 12

The light source (unpolarized light)

———–>polarising filter (polarised light)

———->polarised light passes through compartment containing sample

———–>