Nessie

The more intense infrared absorption for H2O is observed at 3300 cm-1.

1) Assuming that the vibration mode at 3300 cm-1 is also active in Raman spectroscopy, calculate the wavelength of the Stokes Raman line length observed (in nm) by deduction knowing that the fluorescence spectrum of the excited state of water is at λ = 390 nm

Could some one please explain what transitions are taking place for each of the three cases before explaining the answer. Thank you

Write thé half equations for thé following couples:

HNO3/N2O4

N2O4/HNO2

HNO2/N2O

N2O/N2

Any help appreciated, thank you.

Une site de web/un livre/un livre pour le tablet...?

Initially it seems obvious that this would occur however:

Back bonding takes place into the pi* of a X-Y type Ligand (eg NO+, CO, RNC).

For a stronger bonf the MO is lower energy and so antibonding is high in energy.

If this is the case the metal centre is donating into a HIGHER pi* for more electronegative ligands.

However:

The antibonding orbital will be polarised towards the less electronegative part of X-Y (eg N in NO+)

Any ideas?

Whereas CO can recieve pi backdonation THF lone pairs are only available through sigma bonding.I think its something to do with the shape through group theory..

Suggest why the back bonding strength of these ligands decreases in the order C-Se > C-S > CO

I ask this since the donation is occuring into a lower pi* each time AND the repulsion from lp electrons will be significantly reduced since going down the group the lp will be held closer which would suggest a reversal in this trend. I considered the d block contraction for C-Se however this wouldn't explain it.

What change could you make to the spectrum to move either the CO or MH absorbance in the spectrum in order to help determine which is which?

Thank you

I assume 1,1 1,2 and 1,3 diacetylferrocene... But only 1,1 would form.

Is this correct? Any IR/NMR data to back this up?

I am looking fo examples of the Wittig reaction in industry - particularly if related to medicine.

If not, why? Are there better alternatives?

Recently returned something (by collection) to ASDA. Does anyone know how long it will be until I am refunded the cost of this product?

Qu'est-ce que cela signifie?

En septembre, je me déplace en France pour étudier la chimie (BAC +3) à l'université comme étudiant Erasmus.

Je dois choisir les choses que je veut etudier. En Angleterre, nous avons 120 «crédits» à utiliser chaque année et un cours de 8 cours magistraux est généralement de 10 crédits.

En Angleterre, je choisirais 12 cours de 10 crédits.

12 x 10 = 120.

Comment ça marche en France? Je suis très confus!

Même si vous ne pouvez pas répondre à ma question, aucune information au sujet des universités françaises est utile.

For quadrule bond formation 4 electrons are requried from each metal. Here 5 are available. Does the fact that a pair of e-'s would go into the delta star orbital mean that it is energietically favorable to do something else? The delta star isnt THAT high though... although there is chlorine cholrine eclipising.

Any ideas?

My ideas were:

Group 16:

Increase in size down table therefore Oxygen is too small to fit 6 atoms around it (even F).

Po Lb have 6s inert pair so could only form tetra halides.

Halogens:

Most e-neg in their rows

F resists oxidation in hexahalide complexes by delocalising two electrons?

Anything else/more chemically correct?

Exam question:

A typical CH-stretching vibration occurs around 3000cm-1, an NH-stretch around 3350 and an OH around 3600. Explain this trend.

Originally thought that increased bond strength meant increased wavenumber, but this doesnt fit with the average bond strength values of CH (413 kJ/mol), NH (391 kJ/mol) and OH (463 kJ/mol)...

An explained answer would be really helpful!! Thank you

lone pair donation into empty p orbital? If so why doesn't this happen for carbon?