Practical: making and testing the smell of some esters in the lab
3 marks · EasyA student is making propyl ethanoate in the laboratory.
Write the names of the starting alcohol and carboxylic acid.
Name the layer that will float on the water after adding sodium carbonate solution.
State why the ester floats on water, but the alcohol and acid do not.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Propan-1-ol and ethanoic acid
(b) Ester (propyl ethanoate) layer
(c) Esters are less dense and hardly soluble in water, while alcohols and acids dissolve in water.
Common mistakes: Naming the wrong reactants; Confusing solubility and floating
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Writes both correct reactants: propan-1-ol and ethanoic acid.
B2 (b) · 1 mark · Identifies the ester (propyl ethanoate) layer as floating on water.
B3 (c) · 1 mark · States esters are less dense/hardly soluble in water; acids/alcohols dissolve.
Worked solution
(a) The starting alcohol is propan-1-ol and the acid is ethanoic acid.
(b) The ester layer (propyl ethanoate) floats on the water.
(c) Esters hardly dissolve in water, and are less dense, so they float. Acids and alcohols dissolve in water due to hydrogen bonding.