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Sch 2108 – Chemistry Ii Question Paper

Sch 2108 – Chemistry Ii

Course:Bachelor Of Science In Mechatronics

Institution: Dedan Kimathi University Of Technology question papers

Exam Year:2013

SCH 2108 - Chemistry II, Semester - II 2012/2013 Page 1 of 4
DEDAN KIMATHI UNIVERSITY OF TECHNOLOGY
UNIVERSITY EXAMINATIONS 2012/2013
YEAR ONE SEMESTER II EXAMINATION FOR DEGREE OF
BACHELOR OF SCIENCE – MECHATRONIC, ELECTRICAL & ELECTRONICS
SCH 2108 – CHEMISTRY II
Main examination
DATE: April 2013 TIME: 2 Hours
INSTRUCTIONS: Answer Question ONE and any other TWO questions
QUESTION ONE (30 MARKS)
a) Distinguish between (8mks)
(i) Saturated and unsaturated compounds
(ii) Addition and condensation polymerization
(iii) Aliphatic and aromatic compounds
(iv) Glucose and fructose
b) Explain the meaning of the following terms (4mks)
(i) Heterocyclic compounds
(ii) Secondary carbon
(iii) Thermoplastic polymers
(iv) Peptide bonds
c) Give the IUPAC name of the following molecules (6mks)
SCH 2108 - Chemistry II, Semester - II 2012/2013 Page 2 of 4
d) Briefly, explain the term octane number. How can octane number of petrol be
increased. (3mks)
e) Explain why alcohols have a higher boiling point than their corresponding
Alkanes. (3mks)
f) State Markownikoff’s rule (1mk)
g) An alkene X on ozonolysis followed by reacting with Zn/H2O, gives CH3 CH2 CHO
and HCHO.
Give the structure of X? (1mk)
Give the structure formed if X was oxidized with acidic potassium permanganate
solution (2mks)
h) State two advantages of non-soapy over soapy detergents (2mks)
QUESTION TWO (20 MARKS)
a) Describe by use of relevant equations, two general methods for preparation of
alkenes. (4mks)
b) Complete the following reactions by giving the name and structure of the product(s)
formed;
NaNH2 CH3CH2Br
i) CH3C CH ? ? (2mks)
ii) CH3CH2- C = CHCH3 + HBr Peroxide ? (1mk)
CH3
O H
Co n c. HNO 3
iii) ?
(2mks)
O
1) H2O
iv) CH3MgBr + CH3CH2-C-H ? (2mks)
2) HCl
Polymerise
v) CH CH + HCl CH2 CHCl ? (1mk)
c) Distinguish between
(i) Chain-reaction polymerization and step-reaction polymerization (2mks)
(ii) Hard and soft water (2mks)
d) Explain the following observations
(i) The melting point of hexane is higher than that of 2,3 di-methyl butane and yet
they have same molecular formulae (2mks)
(ii) Ethene gas is collected over water after dehydration of ethanol (2mks)
SCH 2108 - Chemistry II, Semester - II 2012/2013 Page 3 of 4
QUESTION THREE (20 MARKS)
a) Explain why aldehydes are more reactive than ketone (2mks)
b) Addition of HBr to unsymmetrical alkenes in presence of organic peroxide is said to
form antimarkrnikov’s product while HCl and HI do not. Explain. (4mks)
c) An organic compound C3H6O (A) gives on oxidation, C3H6O2 (B). A reacts with
ethylmagnesium iodide followed by acid hydrolysis to give C5H12O (C), which on
dehydration gives C5H10 (D). With acid permanganate, D is oxidized to B and
C2H4O2 (E). Identify the compounds A to E. (5mks)
d) Polyethylene is produced by polymerization of ethylene using the famous Ziegler-
Natta catalyst.
(i) Identify the Ziegler-Natta catalyst (1mk)
(ii) State two advantages of polymerization with Ziegler-Natta catalyst over freeradical
polymerization (2mks)
e) Distinguish between fat and oil (2mks)
f) Explain how you would distinguish between primary, secondary and tertiary alcohols.
(3mks)
g) Explain what you understand by vulcanization of rubber (1mk)
QUESTION FOUR (20 MARKS)
a) Alkanes react with halogens to give halogenoalkanes (alkyl halides).
i) State the necessary conditions for the reaction to take place? (2mks)
ii) Why is this method not a good way of making halogenoalkanes. (2mks)
iii) When methane reacts with chlorine the products vary with the amount of chlorine
in the mixture. Explain. (2mks)
b) Name and draw the structures of alkanes that would be formed when Iodoethane is
reacted with 2-iodopropane in the Wurtz reaction? (3mks)
c) State two properties of amino acids. (2mks)
d) Write the structure and IUPAC names for the alcohols with molecular formula
C3H8O. (2mks)
e) Phenol is more acid than ethanol. Explain this observation (2mks)
f) Distinguish between aerobic and anaerobic respiration (3mks)
g) Explain the importance of the Lindler’s catalyst in the preparation of alkenes from
alkynes. (2mks)
SCH 2108 - Chemistry II, Semester - II 2012/2013 Page 4 of 4
QUESTION FIVE (20 MARKS)
a) When Fehling’s solution is mixed with starch no reaction takes place when warmed
gently. However, after a prolonged heating, the solution turns green. Explain.
(2mks)
b) A test tube contains a liquid X, which is known to be one of the substances; methanal,
(formaldehyde), ethanal, (acetaldehyde) or propanone (acetone). Describe the
chemical tests which you would carry out on X to establish its identity. Include
chemical names of reagents, equations for the reactions and observations in each case.
(6mks)
c) Using chemical equations for the reactions, illustrate the reactivity of phenol due to
the ring using;
i) Bromine in non-aqueous solvent (e.g. CS2)
ii) Dilute nitric acid
Give the structures and names of the products formed in each case. (4mks)
d) A polyester is derived from ethan-1,2-diol and benzene-1,4-dicarboxlic acid
i) Draw the structural formulae of the monomers forming this polymer. (2mks)
ii) Show the repeating unit in this polymer. (2mks)
e) State any three uses of polymers (3mks)
f) Explain what you understand by the term Essential amino acid. (1mk)

Sch 2108 – Chemistry Ii Question Paper

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