Date | May 2017 | Marks available | 1 | Reference code | 17M.3.sl.TZ2.10 |
Level | SL | Paper | 3 | Time zone | TZ2 |
Command term | Deduce | Question number | 10 | Adapted from | N/A |
Question
Monosaccharides can combine to form disaccharides and polysaccharides.
Identify the functional groups which are present in only one structure of glucose.
Sucrose is a disaccharide formed from -glucose and β-fructose.
Deduce the structural formula of sucrose.
Starch is a constituent of many plastics. Suggest one reason for including starch in plastics.
Suggest one of the challenges scientists face when scaling up the synthesis of a new compound.
Markscheme
Only in straight chain form:
carbonyl
OR
aldehyde
Only in ring structure:
hemiacetal
Accept functional group abbreviations (eg, CHO etc.).
Accept “ether”.
[2 marks]
correct link between the two monosaccharides
Correct 1,4 beta link AND all bonds on the 2 carbons in the link required for mark.
Ignore any errors in the rest of the structure.
Penalize extra atoms on carbons in link.
[1 mark]
plastic «more» biodegradable/degrades into nontoxic products
OR
plastic can be produced using green technology/renewable resource
OR
reduces fossil fuel use/petrochemicals
OR
easily plasticized
OR
used to form thermoplasts
[1 mark]
minimize «negative» impact on environment
OR
minimize waste produced
OR
consider atom economy
OR
efficiency of synthetic process
OR
problems of side reactions/lower yields
OR
control temperature «inside large reactors»
OR
availability of starting/raw materials
OR
minimize energy costs
OR
value for money/cost effectiveness/cost of production
[1 mark]