EM spectrum & spectrometry laws

Question 1

Describe the relationship between energy, wavelength & frequency?

Answer 1

Wavelength increases= frequency decreases= energy decreases

Question 2

Equation that links speed of light to frequency and wavelength?

Answer 2

C = frequency X wavelength

C–> speed of light

Question 3

which part of the spectrum is most useful in pharm analysis?

Answer 3

UV / Vis / IR- in increasing wavelength

Question 4

Equation that links energy to frequency?

Answer 4

E = hf
E = hc/wavelength
h–> planks constant

Question 5

What are photons?

Answer 5

A quantum of light or electromagnetic radiation which compromises EMR waves

Question 6

What happens when photon hits mater?

Answer 6

The energy can be absorbed, emitted or scattered

Question 7

When does absorption occur?

Answer 7

When e- promoted from low energy state to higher

Question 8

When does excitation occur?

Answer 8

When excited particles return to ground state

Question 9

Change in energy must = to?

Answer 9

Change in energy= E1 - Eo

Question 10

Function of a spectrophotometer?

Answer 10

Recordds absorbance at different wavelengths

Question 11

Most drugs absorbs which range of wavelengths?

Answer 11

UV- except coloured drugs

Question 12

Are the absorbance peaks sharp?

Answer 12

Not sharp- broad due to vibrational levels being present with each electronic level- its of jumps–> converted to broad band

Question 13

What are sigma bonds?

Answer 13

Single bonds

Question 14

What are pi bonds?

Answer 14

Double/ triple bonds

Question 15

Uses of UV absorption?

Answer 15

• ID of drugs
• measuring reactions such as pKa, solubility, ionisation
• quantification of drugs

Question 16

What is the right shift called?

Answer 16

Bathochromic- red

Question 17

What is left shift?

Answer 17

Hypsochromic shift- blue

Question 18

What is up shift?

Answer 18

Hyperchromic

Question 19

What is down shift?

Answer 19

Hypochromic

Question 20

What is conjugation?

Answer 20

Alternating single double bonds

Question 21

Presence of conjugation shifts absorbance to?

Answer 21

Bathochromic- longer wavelength

Question 22

What is the correlation between Abs & conjugation?

Answer 22

No conjugation = weak absorption

Question 23

what is an Auxochrome

Answer 23

A funtioonal soup with lone pairs e.g. OH / NH2

They do not absorb much light on their own

Question 24

What shift do Auxochromes cause?

Answer 24

Bathochromic, Hyperchromic

Question 25

What is a chpormophore?

Answer 25

A part of the molecule which absorbs UV/ Vis light- double bonds or groups with lone pairs of e-

Question 26

Usual distance of cuvette?

Answer 26

1cm- path length- distance that a light travels

Question 27

How to calc amount of light transmitted?

Answer 27

``` T = I / Io OR %T= 100XT T= transmission I = coming out Io= going in ```

Question 28

What is the correlation between conc, abs & transmission?

Answer 28

As conc increases, absorption increases & transmission decreases

Question 29

Equation linking abs & T?

Answer 29

A = log(1/T) = log Io/I

Question 30

What is the Beer- Lambert Law?

Answer 30

``` A = Ebc e= molar extinction coefficient - mcm- b= path length - usually 1cm c= conc- mol/L ```

Question 31

Equation linking Conc & Abs?

Answer 31

C = A / A1%1cm | conc- g/100ml

Question 32

Is the relation between abs & conc linear?

Answer 32

A directly proportional to C until A < 1.5- after that very little transmission and dilution is required- can multiply with dilution factor