CEM1000W - Tutorial 8 - WFP3 - Solutions PDF

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Summary

This is the tutorial of week 8 solutions only...

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DEPARTMENT!OF!CHEMISTRY! ! University!of!Cape!Town! Rondebosch,!7701! South!Africa!

! ! CEM1000W!–!TUTORIAL!8!–!2018!(WFP!3)! ! ! ! SOLUTIONS! ! ! Question!1! ! ! a) C2F2:%! F C CF ! F C C F ! AX2 ! (for both C atoms) ! ! ∴ !Linear!molecule!with!sp!hybridisation.! ! 2p 2p 2p 2p 2p ! 2sp 2sp Mix Orbital!diagram:! forms the 2 2s π bonds ! forms the 2 σ bonds Isolated)C)atom ! (1 to C and 1 to F). ! ! 2p y

x

y

y

∴!

sp

F

2p

z

z

C

2py

2pz

sp

sp

C

2pz

sp

F

! 2p 2p 2p 2p ! ! ! b) COCl2:!! (Note: AX3 - Trig. planar) % ! ! ! ! ! AX3 (Trigonal planar) ! ! ∴ !Trigonal!planar!molecule!with!sp2!hybridization.! ! Orbital!diagrams:! ! 2p 2p 2p 2p forms the 2p 2p 2p ! π bond to O 2sp 2sp 2sp Mix 2s ! 2s ! forms 3 Isolated)C)atom ! σ bonds (2 to Cl and 1 to O) Isolated)O)atom ! !

2p

z

z

y

O Cl C Cl

x

y

y

O C

Cl

Cl

z

z

x

2

2

y

2pz

z

lone pairs

2

Mix

2sp2

2sp2

2sp2

forms the π bond to C

accomodates 2 lones piars and 1 σ bond to C.

sp2

! ! ! ! ! !

2pz

sp2 O

2pz

sp2

π bond to O

sp2 2pz

C 2

2pz

sp 2

2p

! sp ! Cl ! Cl 2p ! ! ! c) OCN-:! Convince yourself that this is the correct Lewis structure. The ‘other’ % would place -1 formal charge on N. Since O is the more electronegative, this is then the ! correct structure. ! ! O C N O C N OC N ‘other one’ ! ! AX2 - Linear ! ∴ !Linear!molecule!with!sp!hybridization.! ! Orbital!diagrams:! ! 2p 2p 2p 2p 2p 2p 2p 2p 2p 2p ! lone pair 2sp 2sp 2sp 2sp Mix Mix ! 2s 2s forms the 2 forms the 2 π bonds to N π bonds to C ! forms the 2 accomodates 1 lone pair Isolated)N)atom Isolated)C)atom ! σ bonds (1 to O and 1 to N) and 1 σ bond. ! ! 2p 2p 2p ! 2p ! sp sp sp sp N C 2p O ! 2p 2p 2p ! 2p ! ! d) CH3OH:% % AX4 - Tetrahedral H ! H ! H C OH H C O ! ! H AX2E2 - Tetrahedral H H ! ! Orbital!diagrams:! ! 2p 2p 2p 2p 2p 2p ! lone pairs 2sp 2sp 2sp 2sp 2sp 2sp 2sp 2sp ! Mix Mix 2s 2s ! accomodates 2 σ bonds forms 4 σ bonds ! Isolated)C)atom Isolated)O)atom (1 to C and 1 to H) and 2 lone (1 to H (x3) and 1 to O) ! pairs of e-. ! y

x

y

y

z

x

z

y

y

z

z

y

z

z

z

z

x

y

y

y

x

z

3

3

3

3

y

z

3

3

3

3

H ! ! sp3 ! 3 H sp3 C sp ! sp3 ! ! H ! ! Question!2:! ! (a) AX2E;!bent!or!V-shaped;!sp2!hybridised.! (b) AX4;!tetrahedral;!sp3.! (c) AX2;!linear;!sp.! (d) AX3;!trigonal!planar;!sp2.! (e) AX4;!tetrahedral;!sp3.! (f) AX2E2;!bent!or!V-shaped;!sp3.! (g) AX3E;!trigonal!pyramidal;!sp3.! (h) AXE2;!trigonal!planar;!sp2.!

sp3 3 sp3 O sp

sp3 H...