Jump to content

Rep:MOD:OOR10969

From ChemWiki

Introduction

NH3,N2,H2 and CLF molecules were investigated by using Gaussian to find out their structural information and optimal energies. Reaction energies that calculated by using optimal energies were compared with literature values.

NH3 molecule

1. NH3 Bond Length/ Bond Angle/ Point Group

bond length bond angle point group
1.01798 105.741 C3v

2. Calculation Method& Basis set

Calculation Method Basis Set
RB3LYP 6-31G(d,p)

3. final energy E(RB3LYP) in atomic units (au)

-56.55776873 a.u.

4. RMS gradient

0.00000485 a.u.

5. 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
Predicted change in Energy=-5.986279D-10
Optimization completed.
   -- Stationary point found.
                          ----------------------------
                          !   Optimized Parameters   !
                          ! (Angstroms and Degrees)  !
--------------------------                            --------------------------
! Name  Definition              Value          Derivative Info.                !
--------------------------------------------------------------------------------
! R1    R(1,2)                  1.018          -DE/DX =    0.0                 !
! R2    R(1,3)                  1.018          -DE/DX =    0.0                 !
! R3    R(1,4)                  1.018          -DE/DX =    0.0                 !
! A1    A(2,1,3)              105.7412         -DE/DX =    0.0                 !
! A2    A(2,1,4)              105.7412         -DE/DX =    0.0                 !
! A3    A(3,1,4)              105.7412         -DE/DX =    0.0                 !
! D1    D(2,1,4,3)           -111.8571         -DE/DX =    0.0                 !


6. Jmol

NH3

The optimisation file is linkd to here


7. IR Vibrations

Display Vibrations Window.


6 modes are expected according to 3N-6 rule. 3*4-6=6 Mode 2 and 3 are degenerate. Mode 5 and 6 are degenerate. Because they have the same frequency thus they have the same energy. Mode 1,2 and 3 are bending vibrations. Mode 4,5 and 6 are stretching vibrations. Mode 4 is highly symmetric. Mode 1 is the umbrella mode. 2 bands (Mode 1 and Mode 2/3) would be expected to see in an experimental spectrum as these 2 modes have large dipole moment changes and thus they have relatively high intensities on the spectrum.

8. Charge

N charge H charge
-1.125 0.0375

For N atom, negative charge is expected. For H atom, positive charge is expected. This is because N atom is more electronegative than H atom.

N2 molecule

1. N2 Bond Length/ Bond Angle/ Point Group

bond length bond angle point group
1.10550798 linear D*H

2. Calculation Method& Basis set

Calculation Method Basis Set
RB3LYP 6-31G(d,p)

3. Final energy E(RB3LYP) in atomic units (au)

-109.52412868 a.u.

4. RMS gradient

0.00000060a.u.

5. 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
Predicted change in Energy=-3.383641D-13
Optimization completed.
   -- Stationary point found.
                          ----------------------------
                          !   Optimized Parameters   !
                          ! (Angstroms and Degrees)  !
--------------------------                            --------------------------
! Name  Definition              Value          Derivative Info.                !
--------------------------------------------------------------------------------
! R1    R(1,2)                  1.1055         -DE/DX =    0.0                 !
--------------------------------------------------------------------------------

6. IR Vibrations

Display Vibrations Window.

As the diatomic rule suggests 3N-5, 3*2-5=1 only one peak would be observed on the spectrum.

8. Jmol

N2

The optimisation file is linkd to here

9. Charge

N charge N charge
0 0

Nitrogen is a homonuclear diatomic molecule therefore zero charge would be expected.

H2 molecule

1. H2 Bond Length/ Bond Angle/ Point Group

bond length bond angle point group
0.60000 linear D*H

2. Calculation Method& Basis set

Calculation Method Basis Set
RB3LYP 6-31G(d,p)

3. final energy E(RB3LYP) in atomic units (au)

-1.17853936 a.u.

4. RMS gradient

0.00000017a.u.

5. 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
Predicted change in Energy=-1.167772D-13
Optimization completed.
   -- Stationary point found.
                          ----------------------------
                          !   Optimized Parameters   !
                          ! (Angstroms and Degrees)  !
--------------------------                            --------------------------
! Name  Definition              Value          Derivative Info.                !
--------------------------------------------------------------------------------
! R1    R(1,2)                  0.7428         -DE/DX =    0.0                 !
-------------------------------------------------------------

6. IR Vibrations

Display Vibrations Window.

As the diatomic rule suggests 3N-5, 3*2-5=1 only one peak would be observed on the spectrum.

7. Jmol

H2

The optimisation file is linkd to here


8. Charge

H charge H charge
0 0

Hydrogen is a homonuclear diatomic molecule therefore zero charge on hydrogen would be expected.

Reaction Energy

E(NH3) E(N2) E(H2)
-56.55776873 a.u. -109.52412868 a.u. -1.17853936 a.u.
2*E(NH3) 3*E(H2) ΔE
-113.1155375 a.u. -3.5356181 a.u. -0.11356825 a.u.

ΔE=2*Energy(NH3)-[Energy(N2)+3*Energy(H2)]=-0.0556326 a.u.=-146.06 Kj/mol

This is the enthalpy required to make 2 mol of NH3

ammonia product is more stable than the gaseous reactants as the reaction is exothermic.

compare with literature value

The literature value of standard enthalpy of formation is -46.2KJ/mol and it differs quite a lot from the calculated value -73.03 KJ/mol [1] </references>

Project molecule--CLF

1. CLF Bond Length/ Bond Angle/ Point Group

bond length bond angle point group
1.66434 linear C*V

2. Calculation Method& Basis set

Calculation Method Basis Set
RB3LYP 6-31G(d,p)

4. final energy E(RB3LYP) in atomic units (au)

-559.94269578 a.u.

5. RMS gradient

0.00014211 a.u.

6. Item 

    Item               Value     Threshold  Converged?
Maximum Force            0.000246     0.000450     YES
RMS     Force            0.000246     0.000300     YES
Maximum Displacement     0.000433     0.001800     YES
RMS     Displacement     0.000613     0.001200     YES
Predicted change in Energy=-1.066054D-07
Optimization completed.
   -- Stationary point found.
                          ----------------------------
                          !   Optimized Parameters   !
                          ! (Angstroms and Degrees)  !
--------------------------                            --------------------------
! Name  Definition              Value          Derivative Info.                !
--------------------------------------------------------------------------------
! R1    R(1,2)                  1.6643         -DE/DX =   -0.0002              !
--------------------------------------------------------------------------------

7. Jmol

CLF

The optimisation file is linkd to here

8. IR Vibrations

Display Vibrations Window.


As the diatomic rule suggests 3N-5, 3*2-5=1 only one peak would be observed on the spectrum.

9. Charge

CL charge F charge
0.309 -0.309

The charge of florine is expected to be negative and the charge of chlorine is expected be positive as florine is more electronegative than chlorine.


Jmol of chlorine
CL2

The optimisation file is linkd to here

Reaction Energy

CL2 energy F2 energy
-920.34987886 a.u. -199.49825218 a.u.

ΔE=Energy(ClF)-[Energy(Cl2)+Energy(F2)]/2=-0.01863026 a.u.=-48.92 KJ/mol

This is the enthalpy required to make 1 mole of ClF

11. Compare with literature value

The literature value of standard enthalpy of formation is -56.5KJ/mol and it is relatively close to the calculated value -48.92 KJ/mol [2] </references>

Jmol of Florine

F2

The optimisation file is linkd to here


10. Molecular Orbitals

This is the antibonding combination between 3s orbital in Cl and 2s orbital in F. Molecular orbital is occupied and in the HOMO region. Cl contributes more in the antibonding orbital.This is because 3s orbital in Cl is higher in energy than 2s orbital in F therefore 3s orbital in Cl contributes more in to the antibonding orbital.


This is the bonding combination between 3s orbital in Cl and 2s orbital in F.As F is more electronegative in the occupied bonding orbital therefore it distorts more electron density towards itself.


This is an occupied bonding combination between 3pZ orbital in Cl and 2pZ orbital in F.

This is an occupied antibonding combination between 3p orbital in Cl and 2p orbital in F. The molecular orbital is the HOMO. Decreasing electron density between nuclei weaken the bonds.

This is an occupied bonding combination between 3p orbital in Cl and 2p orbital in F.

  1. ↑ http://nshs-science.net/chemistry/common/pdf/R-standard_enthalpy_of_formation.pdf
  2. ↑ https://en.wikipedia.org/wiki/Chlorine_monofluoride.
Retrieved from "https://chemwiki.ch.ic.ac.uk/index.php?title=Rep:MOD:OOR10969&oldid=815223"