List the building blocks of triglycerides and carbohydrates.

The drain pipe of a kitchen sink can become clogged by fatty acids, such as linoleic acid, C₁₈H₃₂O₂, but not by the trisaccharide, raffinose, C₁₈H₃₂O₁₆, containing the same number of carbon atoms.

Explain why raffinose is far more water soluble than linoleic acid.

Solid fat triglycerides can also clog kitchen sink drains.

Explain how sodium hydroxide unblocks the drain.

The amount of proteins, fats and carbohydrates determine the energy content of foods.

Explain why linoleic acid, C₁₈H₃₂O₂, is a more efficient energy storage molecule than raffinose, C₁₈H₃₂O₁₆.

Triglycerides:
organic acid/fatty acid and glycerol/propane-1,2,3-triol

AND

Carbohydrates:
monosaccharides

Accept simple sugars.

[1 mark]

«water/aqueous solubility depends on forming many» H-bonds with water

raffinose has many hydroxyl/O–H/oxygen atoms/O «and forms many H-bonds» AND linoleic acid has few/one hydroxyl/O–H/oxygen atom/O/carboxyl group/ COOH/is largely non-polar «and cannot form many H-bonds»

Accept statement which implies comparison.

[2 marks]

«base» hydrolysis/saponification
OR
«produces glycerol and» soap/salt of the «fatty» acid

«products are» water soluble «and drain away»

Accept condensed formulas.

Accept non-balanced equation.

Accept “RCOONa”.

[2 marks]

linoleic acid/C₁₈H₃₂O₂ combustion/oxidation more exothermic «per mol»

linoleic acid/C₁₈H₃₂O₂ has lower proportion/number of O atoms
OR
linoleic acid/C₁₈H₃₂O₂ is less oxidized

Accept converse arguments.

[2 marks]