| Date | May 2016 | Marks available | 2 | Reference code | 16M.3.sl.TZ0.12 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Deduce | Question number | 12 | Adapted from | N/A |
Question
Vegetable oils and diesel fuel have similar energy content but vegetable oils are not usually used as fuels in internal combustion engines.
Transesterification reactions allow waste cooking oils to be converted to biofuels. Identify a reagent and catalyst required for this conversion.
Reagent:
Catalyst:
Deduce the equation for the reaction that occurs assuming that the vegetable oil has the formula drawn below.
Scientists around the world conduct research into alternatives to fossil fuels. Suggest why collaboration is important.
Markscheme
Reagent:
methanol/CH3OH
OR
ethanol/C2H5OH
Do not accept just “alcohol”.
Catalyst:
strong acid
OR
strong base
Accept any strong acid such as sulfuric acid/ H2SO4 .
Accept any strong base such as sodium hydroxide/NaOH.
correct structure of ester product
formula of glycerol AND balanced equation
Do not penalize omission of equilibrium sign.
Accept use of ethanol/other alcohol as reactant with the corresponding products.
Accept full or condensed structural formulas of products.
different solutions/statistical data can be compared/combined
OR
best ideas can be shared to arrive at global/local solutions
OR
acceleration of research
OR
discoveries become available to everyone
OR
improved confidence in validity of results «if multiple scientists/research groups are involved»
OR
money/effort/time is not wasted duplicating work others have already done
Do not accept scientists simply working together to share ideas – look for a little more detail.
Accept other valid suggestions.
