SPECTROMETRY

Question 1

What gives the nuclei of atoms their magnetic moment?

Answer 1

They have a charge and spin

Question 2

What influence does an external magnetic field have on the magnetic moment?

Answer 2

The presence of an external field would cause the magnetic field to all line up in the same direction. However in the absence, the magnetic moment is random.

Question 3

What factors determine how much radio wave energy is required to flip a hydrogen nucleus?

Answer 3

1. High magnetic field - the higher the magnetic field the higher the energy required to flip
2. Electron Density around the hydrogen - Hydrogen nucleus could be shielded by electron density from the magnetic field.

Question 4

Why are integral values very helpful?

Answer 4

They tell us the ratio of H’s in each environment

Question 5

What information can you gain from proton NMR?

Answer 5

1. The chemical shift tells you the environment of the proton (shielded or not shielded)
2. Multiplicity - The number of neighbouring hydrogens
3. Integration of peak area - the ratio of hydrogens in each environment

Question 6

Proton NMR can be used for quantitative and qualitative analysis.
TRUE / FALSE
EXPLAIN

Answer 6

TRUE!
Qualitative - to assess purity or identification
Quantitative - The integral value show us how much H gives rise to a certain peak or environment therefore we can determine how much is present

Question 7

What is the equation to calculate the amount of a compound using proton NMR?

Answer 7

(Number of moles of compound/number of moles of s-trioxane) = (integral of compound/ number of protons giving signal) / (s-trioxane integral / Number of protons giving signal)