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Sch 2101: Chemical Bonding And Structures Question Paper

Sch 2101: Chemical Bonding And Structures

Course:Bachelor Of Science In Medical Microbiology

Institution: Jomo Kenyatta University Of Agriculture And Technology question papers

Exam Year:2012

JOMO KENYATTA UNIVERSITY
OF AGRICULTURE AND TECHNOLOGY

University Examinations 2012/2013

YEAR II SEMESTER II EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE IN MEDICAL MICROBIOLOGY

SCH 2101: CHEMICAL BONDING AND STRUCTURES

DATE: AUGUST 2012 TIME: 2 HOURS

INSTRUCTIONS: ANSWER QUESTION ONE (COMPULSORY) AND ANY OTHER TWO QUESTIONS

QUESTION 1

a) Define the following with examples where possible:

i) Electronegativity (1 mark)

ii) Resonance (2 marks)

iii) Formal charge (2 marks)

iv) Molecular orbital (2 marks)

b) i) What is bonding? (1 mark)

ii) Explain what is an ionic bond. (2 marks)

iii) With examples differentiate between a bond pair and a lone pair of
electrons. (3 marks)

c) i) What is a polar covalent bond? (2 marks)

ii) Name a compound that has polar bonds but is not polar. (2 marks)

d) i) What is the hybridization of atomic orbitals? (2 marks)

ii) What is the difference between a sigma bond and a Pi bond? (3 marks)

e) With examples differentiate between a co-ordinate covalent bond and
a covalent bond. (3 marks)

f) The SO2 present in air is mainly responsible for the acid rain phenomenon.
Its concentration can be determined by titrating against a standard
permanganate solution as follows:

Calculate the number of grams of SO2 in a sample of air if 7.37ml of
0.00800M KMnO4 solution are required for the titration. (5 marks)

(S = 32g; O = 16g)

QUESTION 2

a) Define what is a Lewis diagram. (2 marks)

b) Write Lewis diagrams for the following species showing your working: (9 marks)

i) OF2

ii) N2F2

iii) CN-

(0 = 8, F = 9, C = 6, N = 7)

c) i) Write three reasonable resonance structures for the a zide ion (4 marks)

ii) Show formal charges for any one resonance form. (2 marks)

d) Give three examples of compounds that do not satisfy the octet rule. (3 marks)

QUESTION 3

a) Predict the geometry of the following molecules using VSEPR METHOD. (9 marks)

i) PCl3

ii) CH Cl3

iii) SO3

(P = 15, Cl = 17, C = 6 0 =8)

b) What is the hybridization state of Si in H3 Si – Si H3? (Si = 14) (3 marks)

c) i) Draw a molecular energy level diagram for (B=5). (3 marks)

ii) Calculate the bond order for B2, and comment on their stability
and magnetic properties. (3 marks)

iii) Write the molecular electron configuration for B2. (2 marks)

QUESTION 4

a) Define what are intermolecular forces and intramolecular forces giving
examples. (3 marks)

b) With examples explain the following:

i) Hydrogen bonding (2 marks)

ii) Dipole – Dipole forces (2 marks)

iii) London forces (2 marks)

c) The compounds and ICl have the same number if electrons, yet
melts at – 7.20C and ICl mels at 27.20. Explain . (2 marks)

d) Given the following molecules which are Isomers, explain what you
would expect in their boiling points. (2 marks)

CH3 CH2 – O – CH2 – CH3; CH3 CH2 CH2 CH2 OH

e) List the types of intermolecular forces that exist between molecules in each
of the following species. (4 marks)

i) C6 H6

ii) CH3 Cl

iii) NaCl

iv) CH3CH2 NH2

f) Water is added to 25ml of a 0.866M KNO3 solution until the volume of the
solution is 500ml. Calculate the concentration of the final solution. (3 marks)

Sch 2101: Chemical Bonding And Structures Question Paper

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