NH3

NH3 Information Summary
Molecule:	NH₃
Calculation method:	RB3LYP
Basis Set:	6-31G (d,p)
Final energy (a.u.):	-56.5577687
RMS gradient (a.u.):	0.00000485
Point group:	C_3V
Optimised bond length (A):	1.02
Bond angle (Degrees):	105.7

3-D Structure of Ammonia

The full log file is available at: File:NH3GAUSSFILE 01352190.LOG

Data generated using GaussView

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
 
Predicted change in Energy=-5.986285D-10
 Optimization completed.
    -- Stationary point found.

NH₃ Vibrations

Mode	1	2	3	4	5	6
Wavenumber (cm^-1)	1090	1694	1694	3461	3590	3590
Symmetry	A1	E	E	A1	E	E
Intensity (arbitrary units)	145.38	13.55	13.55	1.06	0.27	0.27

Expected number of vibrations (N=6): 3N-6 = 6

modes 2 and 3 are degenerate

modes 5 and 6 are degenerate

1, 2 and 3 are stretching vibrations

4, 5 and 6 are bending vibrations

4 is highly symmetric

2 bands are expected in the spectrum since there are only two energy levels (due to degeneracy)

Charge distribution:

The charge on each hydrogen atom is +0.239 and the charge on the nitrogen atom is -0.717. It is expected that the nitrogen atom has a slight negative charge and each hydrogen atom has a slight positive charge because nitrogen is more electronegative than hydrogen.

N2

N₂ Information Summary

Molecule:	N2
Calculation method:	RB3LYP
Basis set:	6-31G(D,P)
Final energy (a.u.):	-109.5241287
RMS gradient (a.u.):	0.00000060
Point group:	D*H
Optimised bond length (A):	1.11
Bond angle (Degrees):	180

3-D Structure of N2

     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
 Predicted change in Energy=-3.400972D-13
 Optimization completed.
    -- Stationary point found.

The full log file is available at: File:N2GAUSSFILE 01352190.LOG

Vibrations

Mode	1
Wavenumber (cm^-1)	2457
Symmetry	SGG
Intensity (arbitrary units)	0.00 (not IR active)

Charge distribution:

There are no partial charges on N₂. This is expected since N₂ is a homonuclear diatomic molecule.

H2

H₂ Information Summary

Molecule:	H2
Calculation method:	RB3LYP
Basis set:	6-31G(D,P)
Final energy (a.u.):	-1.1785394
RMS gradient (a.u.):	0.00000017
Point group:	D*H
Optimised bond length (A):	0.74
Bond angle (Degrees)	180

3-D Structure of H2

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
 Predicted change in Energy=-1.164080D-13
 Optimization completed.
    -- Stationary point found.

The full log file is available at: File:H2GAUSSFILE 01352190.LOG

Vibrations

Mode:	1
Wavenumber (cm^-1)	4466
Symmetry:	SGG
Intensity (arbitrary units)	0.00 (not IR active)

Charge distribution:

There are no partial charges on H₂. This is expected since H₂ is a homonuclear diatomic molecule.

The Haber Process Heat Change

N₂ + 3H₂ -> 2NH₃

ΔE=2*E(NH₃)-[E(N₂)+3*E(H₂)]= (2*-56.5577687) - (-109.5241287 + (3*-1.1785394)) = -0.0557907 a.u. = -146.5 kJ/mol

H2 Metal complex

Deposition number: 275803

Database identifier: CEFCAS

H₂ bond length = 1.48 A

The H-H bond length is greater in the metal complex than in H-H gas since electron density is donated from the hydrogen atoms to the Osmium atom in the metal complex. This lowers the bond order of the H-H bond, which increases the H-H bond length in the metal complex.

The 3D structure can be found here[1]

Molecule of choice: Cl2

Molecule:	Cl₂
Calculation method:	RB3LYP
Basis set:	6-31G(D,P)
Final energy (a.u.)	-920.3498789
RMS gradient (a.u.)	0.00002510
Point group:	D*H
Optimised bond length (A)	2.04
Bond angle (Degrees)	180

3-D Structure of Cl2

     Item               Value     Threshold  Converged?
 Maximum Force            0.000043     0.000450     YES
 RMS     Force            0.000043     0.000300     YES
 Maximum Displacement     0.000121     0.001800     YES
 RMS     Displacement     0.000172     0.001200     YES
 Predicted change in Energy=-5.277253D-09
 Optimization completed.
    -- Stationary point found.

The full log file can be found at: File:CL2GAUSSFILE 01352190.LOG

Vibrations

Mode:	1
Wavenumber (cm^-1)	520
Symmetry	SGG
Intensity (arbitrary units)	0.00 (not IR active)

Charge distribution:

There are no partial charges on Cl₂. This is expected since Cl₂ is a homonuclear diatomic molecule.

Cl2 Orbitals

Atomic orbital contributions: 1s

The molecular orbital is a bonding orbital

The molecular orbital is deep in energy

The molecular orbital is occupied by two electrons

The molecular orbital increases the bond order since it is occupied bonding orbital.

Atomic orbital contributions: 2s

The molecular orbital is an antibonding orbital

The molecular orbital is deep in energy

The molecular orbital is occupied by two electrons

The molecular orbital decreases the bond order since it is an occupied antibonding orbital

Atomic orbital contributions: 2s

The molecular orbital is a bonding orbital

The molecular orbital is deep in energy

The molecular orbital is occupied by two electrons

The molecular orbital increases the bond order since it is an occupied bonding orbital

Atomic orbital contributions: 3p

The molecular orbital is a bonding orbital

The molecular orbital is in the HOMO LUMO region

The molecular orbital is occupied by two electrons

The molecular orbital increases the bond order because it is an occupied bonding orbital

Atomic orbital contributions: 3p

The molecular orbital is an antibonding orbital

The molecular orbital is the LUMO

The molecular orbital does not affect the bond order because it is unoccupied

Extension: O2

Molecule:	O₂
Calculation method:	RB3LYP
Basis set:	6-31G(D,P)
Final energy (a.u.)	-150.2574243
RMS gradient (a.u.)	0.00007502
Point group:	D*H
Optimised bond length (A)	1.22
Bond angle (Degrees)	180

3-D Structure of O2

  Item               Value     Threshold  Converged?
 Maximum Force            0.000130     0.000450     YES
 RMS     Force            0.000130     0.000300     YES
 Maximum Displacement     0.000080     0.001800     YES
 RMS     Displacement     0.000113     0.001200     YES
 Predicted change in Energy=-1.033738D-08
 Optimization completed.
    -- Stationary point found.

The full log file can be found at File:O2GAUSSFILE 01352190.LOG

Vibrations

Mode:	1
Wavenumber (cm^-1)	1643
Symmetry	SGG
Intensity (arbitrary units)	0.00 (not IR active)

Charge distribution:

There are no partial charges on O₂. This is expected since O₂ is a homonuclear diatomic molecule.

Marking

Note: All grades and comments are provisional and subject 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 1/1

Is your wiki page clear and easy to follow, with consistent formatting?

YES - easy to follow layout, well done.

Do you effectively use tables, figures and subheadings to communicate your work?

YES

NH3 1/1

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?

YES

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

YES - your answers to the charges question and most of the vibrational questions are good.

However it is due to the low intensity of vibrations 4, 5 and 6 that you only see two peaks in the IR spectrum - there are still 4 separate energy levels!

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 have given a bond angle of 180 for N2 and H2, there are no bond angles in diatomic molecules. Bond angles involve exactly 3 atoms.

Crystal structure comparison 0.5/0.5

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

YES

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

YES - good explanation.

Haber-Bosch reaction energy calculation 0.5/1

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?

No you forgot to answer this question.

Your choice of small molecule 4/5

Have you completed the calculation and included all relevant information?

YES

Have you added information about MOs and charges on atoms?

YES - good explanations on these points.

However you have given a bond angle of 180 for Cl2, there are no bond angles in diatomic molecules. Bond angles involve exactly 3 atoms.

Independence 0.5/1

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

YES - you completed a calculation, well done. However you lost 0.5 for the bond angle again.

Do some deeper analysis on your results so far