[theanonymous]

Ok so I'm not gonna lie, I have no idea how to start this.
What do i do?

[fledarmus]

This first question is just testing a basic understanding of what causes chemical shift. What do you know about shielding and electronegativity in relation to NMR chemical shifts?

[theanonymous]

This first question is just testing a basic understanding of what causes chemical shift. What do you know about shielding and electronegativity in relation to NMR chemical shifts?

I have no idea

[orgopete]

Hint, if methanol were used, its chemical shift would be about 3.3 ppm and methyl flouride would be shifted further.

[theanonymous]

Hint, if methanol were used, its chemical shift would be about 3.3 ppm and methyl flouride would be shifted further.

Yeah but I have absolutely no idea where to even begin interpreting it.
I've been looking at websites like this one: http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/nmr/nmr1.htm and this one: http://iverson.cm.utexas.edu/courses/310N/Handouts/NMRhandout2.html
And it's a whole page of information that I have to dig through...but I don't know what is it in particular that i'm supposed to be looking for in order to answer these kinds of questions

[orgopete]

Yeah but I have absolutely no idea where to even begin interpreting it.
I've been looking at websites like this one: http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/nmr/nmr1.htm and this one: http://iverson.cm.utexas.edu/courses/310N/Handouts/NMRhandout2.html
And it's a whole page of information that I have to dig through...but I don't know what is it in particular that i'm supposed to be looking for in order to answer these kinds of questions

Oh no, not a whole page to read. Okay, begin at Chemical Shifts, and after the box about solvents. It tells you and includes virtually this problem.

[theanonymous]

This first question is just testing a basic understanding of what causes chemical shift. What do you know about shielding and electronegativity in relation to NMR chemical shifts?

Oh!!! Ok so after taking some notes on the sites I looked at..

Each electron in a nucleus will be absorbing energy (particularly electromagnetic radiation of energy)
          - When that energy is being absorbed by the electrons, the nucleus will be converted to a +1/2 spin state to a -1/2 spin state (this is referred to as the “resonance” of that nucleus)
          - The electromagnetic radiation of energy will be absorbed by the nuclei at DIFFERENT frequencies, because of the DIFFERENT electron densities that have a +1/2 and -1/2 spin state
1. Nucleus with GREATER electron density
          a. Nucleus is more shielded from the external magnetic field and isn’t really drawn towards it because there are so many electrons surrounding it that makes it repel the magnetic field
          b. Nucleus absorbs electromagnetic radiation of lower energy (that is, lower frequency)
          c. LOWER electronegativity, farther to the RIGHT
2. Nucleus with LESS electron density
          a. Nucleus is less shielded from the external magnetic field
          b. So nucleus absorbs electromagnetic radiation of higher energy (that is, higher frequency)
          c. HIGHER electronegativity, farther to the LEFT

[theanonymous]

Problem 1) Diagram B is the molecule with the highest electronegativity.

Cl-CH₃ has the highest EN - Diagram B
Br-CH₃ has the second highest EN - Diagram A
I-CH₃ has the lowest EN - Diagram C

Are these answers right?

[theanonymous]

Do I do the same thing here?

[theanonymous]

Problem 2)

CH₃OH - Spectrum D
EtOH - Spectrum B
PrOH - Spectrum A
ⁱPrOH - Spectrum C

That's what I found...
Do I have all those answers right?

[theanonymous]

[theanonymous]

So...

Problem 3)
Acetone - Spectrum C
Acetaldehyde - Spectrum A
Methylacetate - Spectrum B

Is that right?

[fledarmus]

2) and 3) are both right - you catch on quick 

[theanonymous]

2) and 3) are both right - you catch on quick 

Awesome!!