Week 7 Tutorial Sheet

7/25/2019 Week 7 Tutorial Sheet

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Tutorial Worksheet. Week 7 DNA & Polymers

Question 1: DNA and RNA: Nitrogen containing bases and ribose sugars are the two importantchemical structures which bind together to form a nucleoside. a)i) Name the four important N-containing bases in DNA?

a)ii) What is the difference between the N-bases in DNA and RNA

a)iii) Draw the two important sugars in DNA and RNA. Include the numberingof the carbonatoms in these molecules.

b) Name & draw the chemical structure which adds to a nucleoside to give a nucleotide?

c) Draw the chemical structure for a piece of DNA made from the two nucleotides of 2!-deoxyadenosine 5!-monophosphateand 2!-deoxyguanosine 5!-monophosphate. Includenumbering on your sketch where appropriate. Write the base sequence for this pairing.

d) In DNA, how does the double helix form? Illustrate your answer with a sketch.


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Question 2: Describe how each of these strategies would be expected to affect the properties ofpolyethylene.Provide an explanation at the molecular level for each effect.a. increasing the length of the polymer chain:

b. aligning the polymer chains with one another:

c. increasing the degree of branching in the polymer chain:

Question 3: Draw a section of the product formed in the polymerisation of styrene:

Question 4:A sample of polypropylene synthesised in the lab has a molar mass of23,000 g/mol. Approximately how many monomers reacted to form this polymer molecule?

Question 5:

Match the different kinds of intermolecular forces to the three polymers below, which areresponsible for the dominant structural properties for each;

Nylon !-stacking

Polyethylene Hydrogen Bonding

Polystyrene Dispersion Forces


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Question 6:Sketch a section of a copolymer that would be formed when each pair of monomers belowpolymerise. In the space provided, indicate whether this is an example of chain-growth or step-growth, and give the identity of the by-product in this polymerisation reaction. a) glutaric acid and ethylene glycol:

Chain-growth or Step-growth? ________________ By-product? ____________________

b) 1,4-phenylene-diamine and terephthaloyl chloride (makes Kevlar)


c) ethene and tetrafluoroethene


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Week 7 Tutorial Sheet