Question

a. What is/are the name(s) of the functional group(s) that contain oxygen in the two molecules we are using in this lab (ethyl acetate and butyl acetate)?

b. Define “boiling point”.

c. If Compound A has a higher boiling point than Compound B, how do their vapor pressures compare? Choose all of the correct answers among: “A is higher than B”, “B is higher than A”, “A and B are about the same”, “depends on the atmospheric pressure”, or “depends on their relative molecular weights”.

d. Why would distillation not be a good method for separating a mixture of hexane and water? Suggest a better way to separate these two liquids (give the name of a specific piece of chemical apparatus).

e. Make a drawing of the complete distillation apparatus you plan to use. This is to be one single diagram of the whole setup together (not separate diagrams of different sections of it). Make sure you read the procedures carefully regarding specific pieces of equipment to use and modifications compared to Zubrick so you do not include incorrect items. On your diagram, specifically label the following parts: "still pot", the location of "Raschig rings", and the place where the hose attaches for "water in" (from sink). Be sure your diagram clearly illustrates correct positioning of the the (non- mercury) thermometer bulb. You may wish to include a copy of this diagram in your lab notebook so you will be able to refer to it in lab (and also so you can easily annotate it with any last-minute details or procedural changes).

Answer 1

a) The functional group represent ester i.e.- RCOOR'. the COOR' is called as ester functional group. Both of the given compound represnts esters. ethyl acetate(CH₃COOC₂H₅ ) and butyl acetate (CH₃COOC₄H₉)

b) Boiling point is the temperature at which the vapour pressure of the liquid becomes equal to that of the atmospheric pressure. for example, at 100^o the vapour pressure of water becomes equal to that of the atmospheric pressure and it starts to boil.

c) Compound A has a higher boiling point than Compound B - B is higher than A - when the vapour presuure decreases it requires higher temperature to becomes equal to that of atmospheric pressure and hence boiling point increases.

d) distilation is meant for substances that are miscible with each other. Water being a polar solvent anf hexane a non polar solvent, they do not mix with each other and hence distillation is not required here. Rather, a separatory funnel can be used to separate them.