Lesson 3: Optical activity of biomolecules

Question 1

Optical activity

Answer 1

It refers to the ability of a molecule to rotate the plane of polarised light wave

Question 2

Optical Isomers

Answer 2

Molecules will have the same physical properties like solubility, density and melting points but will have different optical properties

Question 3

S vs R isomers

Answer 3

S-Isomers rotate light right (clockwise)
R rotate light left (anticlockwise)

S- are known as + or D (Dextorotary)
R are known as - or L (Levorotary)

Question 4

Plane polarised light reaction with chiral molecules

Answer 4

PPL reacts with a chiral molecule and gets rotated
This process was discovered by Jean-Baptiste Brot in 1815
-He also observed that some compounds rotate light clockiwsie and others anticlockwise

Question 5

what factors affect rotation of plane polarised light

Answer 5

Concentration and nature of chemical substance affects rhe angle and rotation of the plane of polarisation of plane polarised light

Question 6

What is [alpha]

Answer 6

Specific rotation

Question 7

What is the T

Answer 7

It is the temperature which is at 20 degrees Celsius

Question 8

What is the D

Answer 8

-It is the sodium D-line
-It is a specific light from the atomic spectrum of Na with 598nm wavelength
-It is used to standardize measurements

Question 9

What is alpha

Answer 9

-it is the observed rotation
-it represents the rotation degree of the plane of POLARISATION

Question 10

What is the L

Answer 10

-It is the length of the sample (dm)

Question 11

What is C

Answer 11

It is the concentration of the sample (g/ml)