SECTION 2:
SOME SCIENTISTS RESEARCH THE EXTRACTION OF MATERIALS
FROM BIOMASS TO REDUCE OUR DEPENDENCE ON FOSSIL FUELS
NEED FOR ALTERNATIVE SOURCES
Crude oil is a non-renewable resource. While estimates on the available reserves of oil vary,
it is agreed that supply cannot continue to meet the increasing demand. Therefore,
alternative sources of carbon compounds must be developed. Cellulose represents one
major source of carbon compounds, as it contains the basic carbon chain structures that are
needed to build compounds that are presently obtained from petrochemicals.
Cellulose is a major component of biomass. Biomass refers to living and recently dead
biological material that can be used as fuel or for industrial production of useful chemicals.
Chemists, biologists and engineers are developing methods to harvest resources from
biomass to source the necessary raw materials for polymers and other commercially
important carbon based chemicals from cellulose.
QUESTION 29
Identify two important similarities between the components of petroleum and biomass.
Solution
QUESTION 30
Identify two factors causing a need to explore alternative sources of materials used to
produce polymers.
Solution
© The School For Excellence 2016
Trial Exam Revision Lectures – Chemistry – Book 1
Page 19
QUESTION 31 (HSC 2001)
Which of the following is a major component of biomass?
A
Cellulose
B
Ethanol
C
Natural gas
D
Oil
CONDENSATION POLYMERS
Syllabus:
•
Explain what is meant by a condensation polymer.
•
Describe the reaction involved when a condensation polymer is formed.
Condensation polymerisation involves the release of small molecules, such as water,
during the reaction. That is, they are formed from condensation reactions.
For example, in a condensation reaction two hydroxyl groups (a covalently bonded -OH
group – not a hydroxide ion!) from different molecules may react to produce water and leave
an oxygen atom holding the molecules together in a new covalent bond called an ester
bond i.e. C-O-C.
There is no carbon-carbon double bond in a condensation monomer. Good examples of
condensation polymers are Nylon, polyester and cellulose.
QUESTION 32
The diagram below shows the monomer lactic acid, which can polymerise to form polylactic
acid (PLA). Draw a dimer that is produced from lactic acid monomers, and the byproduct of
this reaction.
Solution
© The School For Excellence 2016
Trial Exam Revision Lectures – Chemistry – Book 1
Page 20
CELLULOSE AS A CONDENSATION POLYMER
AND POTENTIAL RAW MATERIAL
Syllabus:
•
Describe the structure of cellulose and identify it as an example of a condensation
polymer found as a major component of biomass.
•
Identify that cellulose contains the basic carbon-chain structures needed to build
petrochemicals and discuss its potential as a raw material.
Cellulose is a biopolymer formed by the condensation polymerisation of glucose monomers.
The figures below show the two structural forms of glucose, alpha-glucose and beta-glucose.
It is the beta form that leads to cellulose formation.
During condensation polymerisation, beta-glucose monomers link together by a beta 1,4glycosidic bond. Up to 10 000 glucose units form the long, unbranched cellulose chain.
This diagram shows that the CH2OH groups on the C-5 position alternate on opposite
sides of the chain. This alternating arrangement maintains a linear structure in the polymer.
It is important that students can recognise the structure of cellulose.
The structure is held together by strong hydrogen bonds between the linear layers. This
makes cellulose insoluble in water, and strong enough to support the cell walls of plants.
© The School For Excellence 2016
Trial Exam Revision Lectures – Chemistry – Book 1
Page 21
QUESTION 33 (HSC 2001:4)
Cellulose is a linear polymer which is a basic structural component of plant cell walls.
Which is the correct representation of part of a cellulose polymer?
© The School For Excellence 2016
Trial Exam Revision Lectures – Chemistry – Book 1
Page 22
QUESTION 34 (HSC 2010:30)
(a)
Compare the process of polymerisation of ethylene and glucose. Include relevant
chemical equations in your answer. (3 marks)
(b)
Explain the relationship between the structures and properties of THREE different
polymers from ethylene and glucose, and their uses. (5 marks)
© The School For Excellence 2016
Trial Exam Revision Lectures – Chemistry – Book 1
Page 23
QUESTION 35 (HSC 2006)
Glucose (C6H12O6) is a monomer that can form naturally occurring polymers.
The approximate atomic weights for the elements which make up glucose are shown in the
table.
Element
Approximate
atomic weight
Carbon
12
Hydrogen
1
Oxygen
16
Using data from the table, what would be the approximate molecular weight of a polymer
made from 5 glucose monomers?
A
B
C
D
810
828
882
900
QUESTION 36 (HSC 2003:20)
Assess the suitability of biomass as a future source of energy and chemicals for industry.
(5 marks)
Solution
© The School For Excellence 2016
Trial Exam Revision Lectures – Chemistry – Book 1
Page 24
BIOPOLYMERS
Syllabus:
•
Use available evidence to gather and present data from secondary sources and
analyse progress in the recent development and use of a named biopolymer. This
analysis should name the specific enzyme(s) used or organism used to synthesise the
material and an evaluation of the use or potential use of the polymer produced related
to its properties.
A biopolymer is a naturally occurring polymer or a polymer that that is produced using
natural resources like plants and micro-organisms. Examples of biopolymers include:
•
Biopol
•
Polyhydroxyalkanoate (PHA)
•
Polyhydroxybutyrate (PHB)
•
Polyhydroxyvalerate (PHV)
•
PHB-PHV copolymer
•
Polylacticacid (or polylactide PLA)
•
Protein based polymers (PBP)
•
Cyclodextrins (CD)
A new branch of biopolymer research and development is taking plant material and
converting it into polyester style polymers using micro-organisms such as bacteria,
e.g. Alcaligenes eutrophus and Ralstonia eutrophus. The monomers produced by the
bacteria are known as PHB’s and PHV’s. This is how they work:
•
Bacteria are fed a diet rich in glucose and valeric acid.
•
Bacteria reproduce rapidly and synthesise and store a copolymer of PHB and PHV.
Commercially, the biopolymer is known as Biopol.
•
Bacteria are separated from the polymers they produce and the polymers used to
replace synthetic polymers in uses such as nappies.
•
Technological advances in genetic engineering can introduce the PHB/PHV producing
genes into rapidly reproducing E. coli – making production more efficient.
An example of a commercially available biopolymer based on PHB’s.
© The School For Excellence 2016
Trial Exam Revision Lectures – Chemistry – Book 1
Page 25
QUESTION 37 (HSC 2002:18)
(a)
Name the type of polymerisation shown in the following reaction:
(Bonus – there is an error in this equation, find and fix it)
(b)
Assess current developments in the use of biopolymers. (4 marks)
© The School For Excellence 2016
Trial Exam Revision Lectures – Chemistry – Book 1
Page 26
QUESTION 38 (HSC 2011:27)
The following extract was taken from a blog about environmental issues.
...the use of long-lasting polymers for short-lived applications can cause problems for the
preservation of living systems...Plastic debris has a costly impact on waste management for
municipalities.
Assess the uses of polystyrene and a named biopolymer in terms of their properties, with
reference to the statements made in this blog. (5 marks)
Solution
© The School For Excellence 2016
Trial Exam Revision Lectures – Chemistry – Book 1
Page 27