Rep:Mod:01495470

NH₃ Molecule

N-H bond distance = 1.01798Å, H-N-H bond angle = 105.741°, Calculation Method = RB3LYP, Basis Set = 6-31G(d,p), Final Energy = -56.55776873au, Point Group C₃v

The optimised file is linked to here

Item

Item               Value     Threshold  Converged?
 Maximum Force            0.000004     0.000450     YES
 RMS     Force            0.000004     0.000300     YES
 Maximum Displacement     0.000072     0.001800     YES
 RMS     Displacement     0.000035     0.001200     YES

Jmol dynamic image

test molecule

Vibrations https://wiki.ch.ic.ac.uk/wiki/index.php?title=File:SCREEN_CAPTURE_NH3_VIBRATIONS.PNG

wavenumber (cm-1)	1089.5	1693.9	1693.9	3461.3	3589.8	3589.8
symmetry	A1	E	E	A1	E	E
intensity	145.4	13.6	13.6	1.1	0.3	0.3

From the 3N-6 rule 6 vibrational modes are present in NH3. There are two pairs of degenerate vibrational modes with wavenumbers 1693.9 and 3589.8. Modes with wavenubers: 1089.5 and 1693.9 are bending and modes with wavenubers: 3461.3 and 3589.8 are stretching. The modes with wavenumbers 1089.5 and 3461.3 are highly symmetric as they have a1 symmetry. The mode with wavenumber 1089.5 is termed the umbrella mode. On the IR spectrum of NH3 there are 4 bands.

Charge Analysis Charge on H atoms - 0.375D Charge on N atom - -1.125D

N₂ Molecule

N-N bond distance = 1.10550Å, N-N bond angle = 180°, Calculation Method = FREQ, Basis Set = 6-31G(d,p), Final Energy = -109.52412868, Point Group D∞H

The optimised file is linked to https://wiki.ch.ic.ac.uk/wiki/index.php?title=File:N2_OPTIMISATION2.LOG

Item

  Item               Value     Threshold  Converged?
 Maximum Force            0.000001     0.000450     YES
 RMS     Force            0.000001     0.000300     YES
 Maximum Displacement     0.000000     0.001800     YES
 RMS     Displacement     0.000000     0.001200     YES

Jmol dynamic image

test molecule

Vibrations https://wiki.ch.ic.ac.uk/wiki/index.php?title=File:N2-Screencapturefrequencies.PNG

wavenumber (cm-1)	2457.33
symmetry	D∞H
intensity	0

Charge Analysis Charge on N atoms - 0D

H₂ Molecule

H-H bond distance = 0.74279Å, H-H bond angle = 180°, Calculation Method = RB3LYP, Basis Set = 6-31G(d,p), Final Energy = -1.17853936, Point Group D∞H

The optimised file is linked to https://wiki.ch.ic.ac.uk/wiki/index.php?title=File:FRASER_H2_OPTIMISATION.LOG

Item

     Item               Value     Threshold  Converged?
 Maximum Force            0.000000     0.000450     YES
 RMS     Force            0.000000     0.000300     YES
 Maximum Displacement     0.000000     0.001800     YES
 RMS     Displacement     0.000001     0.001200     YES

Jmol dynamic image

test molecule

Vibrations https://wiki.ch.ic.ac.uk/wiki/index.php?title=File:H2_screencapture.PNG

wavenumber (cm-1)	4465.68
symmetry	D∞H
intensity	0

Charge Analysis Charge on H atoms - 0D

N₂ Molecule in a complex Unique Conquest Identifier - VECWIM Link to complex - https://wiki.ch.ic.ac.uk/wiki/index.php?title=File:VECWIM.xyz Optimised N₂ bond distance - 1.10550Å, N₂ bond distance in VECWIM - 1.070Å The N-N bond distance is shorter in the complex than it is when lone. This is because the transition metal the N2 ligand is bound to is electron drawing making the N-N bond weaker and therefore shorter. Also the lone N₂ species is in the gaseous state whereas in the complex it is solid.

Haber Bosch Energy Calculation

E(NH3)= -56.55776873 2*E(NH3)= -113.115537 E(N2)= -109.52412868 E(H2)= -1.17853936 3*E(H2)= -3.53561808 ΔE=2*E(NH3)-[E(N2)+3*E(H2)]= -0.055837AU =-146.6KJ/Mol Therefore ammonia is more stable than the gaseous reactants as the reaction is exothermic meaning the internal energy of the system has decreased.

Cl2 Project Molecule

Cl-Cl Bond Distance = 2.04163, H-H bond angle = 180°, Calculation Method = RB3LYP, Basis Set = 6-31G(d,p), Final Energy = -920.34987887, Point Group D∞H

The optimised file is linked to https://wiki.ch.ic.ac.uk/wiki/index.php?title=File:CL2_OPTIMISATION.LOG

Item

         Item               Value     Threshold  Converged?
 Maximum Force            0.000006     0.000450     YES
 RMS     Force            0.000006     0.000300     YES
 Maximum Displacement     0.000016     0.001800     YES
 RMS     Displacement     0.000023     0.001200     YES

Jmol dynamic image

test molecule

Vibrations https://wiki.ch.ic.ac.uk/wiki/index.php?title=File:FraserCl2capture.PNG

wavenumber (cm-1)	520.47
symmetry	D∞H
intensity	0

Charge Analysis Charge on Cl atoms - 0D

Molecular Orbitals

1 This molecular orbital is the lowest in energy in Cl2. It is formed by the in phase side-by-side overlap of the chlorine's 1s orbitals which is a very good overlap which is why the molecular bonding orbital formed is of low energy.

2 This molecular orbital is of slightly higher energy than the first as it is composed of the side-by-side in phase overlap of the chlorine's 2s orbitals which are higher in energy than the 1s orbitals.

3 This molecular orbital is composed of the side-by-side out of phase overlap of the 1s atomic orbitals. This creates an antibonding orbital with one nodal plane. The antibonding moleculra orbital is of higher energy than the bonding orbital as it a lesser effective overlap between the atomic orbitals.

4 This molecular orbital is the highest occupied molecular orbital (HOMO). This is the highest energy molecular orbital that contains electrons. It is a bonding orbital meaning the Cl2 molecule can exist with a bond order of one.

5 This molecular orbital is the lowest unoccupied molecular orbital (LUMO).

Marking

Note: All grades and comments are provisional and subjecct to change until your grades are officially returned via blackboard. Please do not contact anyone about anything to do with the marking of this lab until you have recieved your grade from blackboard.

Wiki structure and presentation 0.5/1

Is your wiki page clear and easy to follow, with consistent formatting? Do you effectively use tables, figures and subheadings to communicate your work?

Your wiki is consistently formatted and you occasionally used tables to structure it. All your jmols are labelled as 'test molecule'. This should be more informative. You have not used subsections very efficiently to make the structure of you wiki clearer but used bold titles instead.

NH3 0.5/1

Have you completed the calculation and given a link to the file?

YES

Have you included summary and item tables in your wiki?

YES

Have you included a 3d jmol file or an image of the finished structure?

YES

Have you included the bond lengths and angles asked for?

YES

Have you included the “display vibrations” table?

YES

Have you added a table to your wiki listing the wavenumber and intensity of each vibration?

YES

Did you do the optional extra of adding images of the vibrations?

NO

Have you included answers to the questions about vibrations and charges in the lab script?

YES, however you stated to expect 4 bands in the experimental spectrum. You correctly stated that there are two sets of degenerate modes - this explains a spectrum with 4 peaks. However there are only 2 peaks visible as peaks 4, 5 and 6 are of too low an intensity to be visible and you have not commented on the intensities at all.

You could have included an electronegativity argument to explain the calculated charges on the atoms. Additionally, the unit of D (Debye) is not used for charges rather than for dipole moments!

N2 and H2 0/0.5

Have you completed the calculations and included all relevant information? (summary, item table, structural information, jmol image, vibrations and charges)

YES - however you stated a bond angle for H2 and for N2. To create a bond angle a minimum of 3 atoms is needed.

Crystal structure comparison 0/0.5

Have you included a link to a structure from the CCDC that includes a coordinated N2 or H2 molecule?

NO - instead you included a .xyz file. This was a nice additional info but you have not included a link to the CCDC. Therefore, we cannot check the source of the given data. Appropriate referencing is important!

Have you compared your optimised bond distance to the crystal structure bond distance?

YES

Haber-Bosch reaction energy calculation 1/1

Have you correctly calculated the energies asked for? ΔE=2*E(NH3)-[E(N2)+3*E(H2)]

YES

Have you reported your answers to the correct number of decimal places?

YES

Do your energies have the correct +/- sign?

YES

Have you answered the question, Identify which is more stable the gaseous reactants or the ammonia product?

YES

Your choice of small molecule 2/5

Have you completed the calculation and included all relevant information?

YES

Have you added information about MOs and charges on atoms?

You could have discussed the calculated vibrations. (How many modes you expected, what is about the intensity...) You could have explained the charges using an electronegativity argument. You should have reoriented the molecule before taking snapshots in that way it is possible to see what is going on between the two atoms. MO1: There is no overlap at all, so this is a nonbonding MO. MO2: For the 2s Mos there still is no overlap. this is a nonbonding MO as well. MO3: This MO is not composed of 1s orbitals. It can be constructed by 2p orbitals and is nonbonding as well. MO4: Your statement is correct. But you missed to mention it is composed of the 3p orbitals of Cl. MO5: Any statement despite the correct assignment as the LUMO is missing.

Independence 0/1

If you have finished everything else and have spare time in the lab you could: Check one of your results against the literature, or Do an extra calculation on another small molecule, or Do some deeper analysis on your results so far

NO - no independent work was identified