1B Fats and oils  /30

    1)          This question is about fatty acids and fats:

                 a)  Draw and name the fatty acid 18:2(9.12)  [2]

                                                    octadec 9,12 dienoic acid

                 b)  Use the shorthand notation for the following molecule  [1]

                                                                  18:1(9)

                 c)  Name the functional groups in the molecule in (b)  [2]

                                carboxylic acid  [1]  alkene  [1]

                 d)  Describe a simple chemical test you could carry out to distinguish between the molecules below  [2]

                                Bromine water  [1]  2nd molecule will change it from orange à  clear and colourless  [1]

                 e)  Write a balanced chemical equation for the reaction between glycerol and hexadecanoic acid. 

                      Circle the new functional group and label it  [3]

                                Triester formula correct [1]  Rest of equation correct [1]  ester group circled and named [1]

    2)          This question is about fats and oils:       

                 a)  Draw the skeletal formulas for a i) saturated fatty acid  ii) trans fatty acid  iii)  cis fatty acid   [3]

                         i)  skeletal formula with no double bonds but a carboxylic acid functional group at the end  [1]

                         ii) skeletal formula with at least 1 double bond, molecule still flat (ish), carboxylic acid at end  [1]

                         iii) skeletal formula with at least 1 double bond, molecule in a 'v' shape, carboxylic acid at end  [1]

                 b)  Use your answers in (a) to explain the health issues associated with each (i) - (iii)  [8]

                         i) and ii)  efficient packing  [1]  strong VDW  [1]  solid causes blockages [1]  heart disease [1]

                         iii)inefficient packing  [1]  weak VDW  [1]  liquid [1]  blockage and heart disease avoided [1]

                 c)  Explain the difference between and fat and an oil  [3]

                                Fats are solids and oils are liquids [1]  fats have stronger IMF of attraction [1]

                                bringing the melting point above room temperature [1]  ORA

                 d)  Use your knowledge of the alkenes to describe how solids (margarine) are formed from oils  [3]

                                C=C are removed by reaction with H₂ [1]  with a nickel catalyst [1]  15^oC  [1]

    3)          Oils can be used to produce fuels.

                 a)  Draw the structure of an oil made between glycerol and hexadecanoic acid:  [1]

                 b)  Write an equation for the formation of biodiesel from the triester in (a)  [2]

                                                          Methyl hexadecanoate [1]

                                                          Rest of the equation  [1]