Download Chemical and Biological Sciences - CIT

Cork Institute of Technology
Bachelor of Engineering (Honours) in Chemical & Process
Engineering – Stage 1
(NFQ – Level 8)
Autumn 2007
CE 1.3 Chemical and Biological Sciences
(Time: 3 Hours)
Answer SIX questions
Answer two questions from Section A
Answer four questions from Section B
Examiners:
Dr. A. Coffey
Dr. P. Moroney
Prof. L. Kershenbaum
Dr. D. O’Connor
Use separate answer books for Section A (Biology)
and Section B (Chemistry)
Section A (Biology)
Q1. (a) Give an account of Fungi with reference to:
(i)
cell structure and cell components;
(ii)
life-cycle;
(iii) where they are found;
(iv) industrial significance.
(b) Give an account of viruses (eg bacteriophage) with reference to:
(i)
structure;
(ii)
typical size;
(iii) life-cycle;
(iv) industrial significance.
Q2. (a) Explain how bacterial culture media are designed to support the growth of bacteria.
(b) Discuss spore formation in Bacteria.
Q3.
Write a detailed account of the four principal marcomolecules in bacteria (Protein,
Carbohydrate, Lipid and Nucleic Acid). Use of diagrams is encouraged.
Section B (Chemistry)
Q4. (a) Show, using appropriate examples, how polar covalent and non-polar (pure)
covalent bonds occur in chemistry.
(6 marks)
(b) Explain whey H2O boils at 100°C whereas H2S, whose relative molecular mass is
greater, is a gas at room temperature.
(4 marks)
(c) Show how metallic bonding can explain why metals are such good conductors of
electricity but why this electrical conductivity decreases with increase in
temperature.
(6 marks)
(d) Explain what is meant by Van der Waals forces.
Describe the influence thy have on the behaviour of molecules.
(4 marks)
Q5. (a) With reference to a chemical reaction, explain the meaning of the terms:
(i)
Order of reaction
(ii)
Activation energy
(b) (i)
(4 marks)
Briefly describe the main principles underlying the collision model theory as
used in reaction kinetics.
(ii)
(6 marks)
Use the collision model theory to account for the effects of reactant
concentration and temperature on reaction rates.
(4 marks)
(c) The decomposition of the gas N2O5 was studied at constant temperature (55°C)
2 N 2 O5 ( g ) → 4 NO2 ( g ) + O2 ( g )
And the following rate data were obtained for the disappearance of N2O5:
[N2O5], mol dm-3
Time, s2
0.020
0.0169
0.0142
0.0120
0.0101
0.0086
0.0072
0
100
200
300
400
500
600
Show graphically whether this reaction is first order or second order and calculate
the value of the rate constant for the reaction.
(6 marks)
Q6. (a) In the elemental analysis of a hydrocarbon compound, outline how the percentages
of hydrogen and carbon are experimentally obtained.
(4 marks)
(b) An organic compound was subjected to elemental analysis. It gave the following
data: carbon 61.9% and hydrogen 10.3%. Its molecular mass was determined to be
116. Determine the empirical and molecular formula for the compound.
Write a possible structure for this compound.
(6 marks)
(c) Define what is meant by constitutional (structural) isomers and, using alkanes as
example, write structures to illustrate your answer.
(4 marks)
(d) The halogenation of an alkane is an example of a free radical substitution reaction.
Taking the reaction of methane with chlorine as an example, show how this reaction
undergoes initiation, then propagation and finally termination.
(6 marks)
Q7. (a) Mention the advantages that the development of the Brönsted-Lowry theory of acids
and bases offered over the earlier Arrhenius theory.
(4 marks)
(b) In the Brönsted-Lowry model of acid-base reactions, what does the statement that
HCl is a stronger acid than H2O mean in terms of the following reaction?
HCl ( aq ) + H 2 O (l ) → H 3+ O ( aq ) + Cl − (aq )
(3 marks)
(c) Calculate the pH value of the following solutions:
(i)
0.05 mol dm-3 KOH
(ii)
4.9 g H2SO4 in 400 cm3 of water
(iii) 0.10 mol dm-3 propanoic acid, CH3CH2COOH
(for propanoic acid, Ka = 1.9 x 10-5 at ambient temperature)
(8 marks)
(d) Explain what is meant by a buffer solution.
State the Henderson-Hasselbalch buffer equation.
(5 marks)
Q8. (a) State Le Chateliers Principle.
(3 marks)
(b) Write an expression for Kp and Kc for the chemical reaction:
2 SO2 ( g ) + O2 ( g )
2 SO3 ( g ), ∆H = − 196 kJ mol −1
(4 marks)
(c) When 0.02 mol of a sample of SO2 is introduced into a 1.48 dm3 reactor at a high
temperature, 0.0138 mol SO3 is found to be present at equilibrium.
Calculate the Kc value for the reaction.
(5 marks)
(d) In the synthesis of ammonia by the Haber process indicate as many ways as possible
of increasing the yield of ammonia product and explain your reasoning.
N 2 ( g ) + 3H 2 ( g )
2 NH 3 ( g ), ∆H = − 92 kJ mol −1
Q9. (a) Outline a chemical test that distinguishes an alkane from an alkene.
(8 marks)
(4 marks)
(b) Draw structures for the following molecules:
2,2,3 – dichloronitrohexane and 2 – methylbut-1-ene.
(4 marks)
(c) State Markownikoff’s Rule and give an example of the rule in operation in
electrophilic addition reactions to alkenes.
(6 marks)
(d) Give the structures of the products when but-1-ene is reacted with the following
reagents:
(i)
bromine
(ii)
water in the presence of a mineral acid
(iii) hydrogen in the presence of platinum catalyst.
(6 marks)