4.4 spectroscopy and chromatography

Question 1

ultra-violet

effect on molecules
uses in chemical analysis
spectroscopy technique

Answer 1

effect on molecules
- causes covalent bond in molecules to break

uses in chemical analysis
- initiation of reaction ( homolytic fission )

spectroscopy technique
-UV spectroscopy

Question 2

infra-red

effect on molecules
uses in chemical analysis
spectroscopy technique

Answer 2

effect on molecules
- causes polar bonds in molecules to vibrate faster

uses in chemical analysis
- identification of bond and functional group

spectroscopy technique
- IR spectroscopy

Question 3

microwaves

effect on molecules
uses in chemical analysis
spectroscopy technique

Answer 3

effect on molecules
- causes polar molecules to rotate faster

uses in chemical analysis
- heating

spectroscopy technique
- microwave spectroscopy

Question 4

radio waves

effect on molecules
uses in chemical analysis
spectroscopy technique

Answer 4

effect on molecules
- causes nuclei in molecules to spin faster

uses in chemical analysis
- determination of structure of molecules

spectroscopy technique
- NMR spectroscopy

Question 5

NMR

what field it uses?
the absorption energy is used to?

Answer 5

magnetic field ( using electromagnet )
radio frequency field 

the absorption energy is used to
to detect proton in organic compound

Question 6

low resolution nmr spectrum

the number of peaks

the chemical shift

Answer 6

the number of peaks
- gives the number of proton environments

the chemical shift
- gives the types of proton environments

Question 7

chemical shift

Answer 7

the distance in the spectrum from the standard peak measured in ppm

tetramethylsilane ( TMS ) used as standard

Question 8

combined techniques

mass spectrometry
infra red spectrometry
NMR spectrometry

give information on

Answer 8

mass spectrometry

• molecular mass ( highest m/e value )
• possible structure ( fragmentation pattern )

infra red spectrometry

• type of bonds ( absorption peak )
• possible functional group ( from wavenumber )

NMR spectrometry

• hydrogen atom environment in a molecule
• comfirms the structure of a molecule

Question 9

kinetic II

rate of reaction defined as

Answer 9

change in concentration of either the reactants or products per unit time

formula pg 1
units

Question 10

kinetic II

experimental technique for studying rate of reaction

name 4

Answer 10

1. measuring volume of a gas
2. monitoring a colour change ( absorbance of solution )
3. monitoring changes in electrical conductivity
4. ” clock reactions “